Extend the tab with 8 whitespace

This work was done as follows:
- check:   `git grep $'\011' -- :^oss-fuzz`
- convert: `ruby -pi -e 'nil while $_.sub!(/^(.*?)\t/) { $1 + " " * (8 - $1.size % 8) }'`

The `doc/guide/{compile,mrbgems}.md` file adds and removes whitespace to make the directory tree look the same.
In `mrbgems/mruby-socket/src/socket.c`, there is a part where the indent is changed from 4 to 2 at the same time as the tab is changed.

2 files changed, 123 insertions, 113 deletions

diff --git a/doc/guides/compile.md b/doc/guides/compile.md
index 7156b2b68..08dbd850f 100644
--- a/doc/guides/compile.md
+++ b/doc/guides/compile.md
@@ -333,9 +333,9 @@ conf.enable_debug
 When debugging mode is enabled
 
 * Macro `MRB_DEBUG` would be defined.
-	* Which means `mrb_assert()` macro is enabled.
+  * Which means `mrb_assert()` macro is enabled.
 * Debug information of irep would be generated by `mrbc`.
-	* Because `-g` flag would be added to `mrbc` runner.
+  * Because `-g` flag would be added to `mrbc` runner.
     * You can have better backtrace of mruby scripts with this.
 
 ## Cross-Compilation
@@ -379,23 +379,25 @@ end
 During the build process the directory `build` will be created in the
 root directory. The structure of this directory will look like this:
 
-	+- build
-	   |
-	   +-  host
-	       |
-	       +- LEGAL        <- License description
-	       |
-	       +- bin          <- Binaries (mirb, mrbc and mruby)
-	       |
-	       +- lib          <- Libraries (libmruby.a and libmruby_core.a)
-	       |
-	       +- mrbc         <- Minimal mrbc place
-	       |
-	       +- mrbgems      <- Compilation result from mrbgems
-	       |
-	       +- mrblib       <- Compilation result from mrblib
-	       |
-	       +- src          <- Compilation result from C sources
+```
++- build
+    |
+    +- host
+        |
+        +- LEGAL        <- License description
+        |
+        +- bin          <- Binaries (mirb, mrbc and mruby)
+        |
+        +- lib          <- Libraries (libmruby.a and libmruby_core.a)
+        |
+        +- mrbc         <- Minimal mrbc place
+        |
+        +- mrbgems      <- Compilation result from mrbgems
+        |
+        +- mrblib       <- Compilation result from mrblib
+        |
+        +- src          <- Compilation result from C sources
+```
 
 The compilation workflow will look like this:
 
@@ -425,31 +427,33 @@ The compilation workflow will look like this:
 In case of a cross-compilation to `i386` the `build` directory structure looks
 like this:
 
-	+- build
-	   |
-	   +-  host
-	   |   |
-	   |   +- bin           <- Native Binaries
-	   |   |
-	   |   +- lib           <- Native Libraries
-	   |   |
-	   |   +- mrbgems
-	   |   |
-	   |   +- src
-       |
-	   +- i386
-	      |
-	      +- bin            <- Cross-compiled Binaries
-	      |
-	      +- include        <- Header Directory
-	      |
-	      +- lib            <- Cross-compiled Libraries
-	      |
-	      +- mrbgems
-	      |
-	      +- mrblib
-	      |
-	      +- src
+```
++- build
+    |
+    +- host
+    |   |
+    |   +- bin           <- Native Binaries
+    |   |
+    |   +- lib           <- Native Libraries
+    |   |
+    |   +- mrbgems
+    |   |
+    |   +- src
+    |
+    +- i386
+        |
+        +- bin            <- Cross-compiled Binaries
+        |
+        +- include        <- Header Directory
+        |
+        +- lib            <- Cross-compiled Libraries
+        |
+        +- mrbgems
+        |
+        +- mrblib
+        |
+        +- src
+```
 
 An extra directory is created for the target platform. In case you
 compile for `i386` a directory called `i386` is created under the
diff --git a/doc/guides/mrbgems.md b/doc/guides/mrbgems.md
index d4160ebc8..9aebb9208 100644
--- a/doc/guides/mrbgems.md
+++ b/doc/guides/mrbgems.md
@@ -111,21 +111,21 @@ contains every gem found in the `mrbgems` directory.
 The maximal GEM structure looks like this:
 
 ```
-+- GEM_NAME         <- Name of GEM
-   |
-   +- README.md     <- Readme for GEM
-   |
-   +- mrbgem.rake   <- GEM Specification
-   |
-   +- include/      <- Header for Ruby extension (will exported)
-   |
-   +- mrblib/       <- Source for Ruby extension
-   |
-   +- src/          <- Source for C extension
-   |
-   +- tools/        <- Source for Executable (in C)
-   |
-   +- test/         <- Test code (Ruby)
++- GEM_NAME             <- Name of GEM
+    |
+    +- README.md        <- Readme for GEM
+    |
+    +- mrbgem.rake      <- GEM Specification
+    |
+    +- include/         <- Header for Ruby extension (will exported)
+    |
+    +- mrblib/          <- Source for Ruby extension
+    |
+    +- src/             <- Source for C extension
+    |
+    +- tools/           <- Source for Executable (in C)
+    |
+    +- test/            <- Test code (Ruby)
 ```
 
 The folder `mrblib` contains pure Ruby files to extend mruby. The folder `src`
@@ -297,19 +297,21 @@ mrb_c_extension_example_gem_final(mrb_state* mrb) {
 
 ### Example
 
-	+- c_extension_example/
-	   |
-	   +- README.md         (Optional)
-	   |
-	   +- src/
-	   |  |
-	   |  +- example.c         <- C extension source
-	   |
-	   +- test/
-	   |  |
-	   |  +- example.rb        <- Test code for C extension
-	   |
-	   +- mrbgem.rake          <- GEM specification
+```
++- c_extension_example/
+    |
+    +- README.md        (Optional)
+    |
+    +- src/
+    |   |
+    |   +- example.c    <- C extension source
+    |
+    +- test/
+    |   |
+    |   +- example.rb   <- Test code for C extension
+    |
+    +- mrbgem.rake      <- GEM specification
+```
 
 ## Ruby Extension
 
@@ -323,19 +325,21 @@ none
 
 ### Example
 
-	+- ruby_extension_example/
-	   |
-	   +- README.md         (Optional)
-	   |
-	   +- mrblib/
-	   |  |
-	   |  +- example.rb     <- Ruby extension source
-	   |
-	   +- test/
-	   |  |
-	   |  +- example.rb     <- Test code for Ruby extension
-	   |
-	   +- mrbgem.rake       <- GEM specification
+```
++- ruby_extension_example/
+    |
+    +- README.md        (Optional)
+    |
+    +- mrblib/
+    |   |
+    |   +- example.rb   <- Ruby extension source
+    |
+    +- test/
+    |   |
+    |   +- example.rb   <- Test code for Ruby extension
+    |
+    +- mrbgem.rake      <- GEM specification
+```
 
 ## C and Ruby Extension
 
@@ -353,23 +357,25 @@ See C and Ruby example.
 
 ### Example
 
-	+- c_and_ruby_extension_example/
-	   |
-	   +- README.md         (Optional)
-	   |
-	   +- mrblib/
-	   |  |
-	   |  +- example.rb     <- Ruby extension source
-	   |
-	   +- src/
-	   |  |
-	   |  +- example.c      <- C extension source
-	   |
-	   +- test/
-	   |  |
-	   |  +- example.rb     <- Test code for C and Ruby extension
-	   |
-	   +- mrbgem.rake       <- GEM specification
+```
++- c_and_ruby_extension_example/
+    |
+    +- README.md        (Optional)
+    |
+    +- mrblib/
+    |   |
+    |   +- example.rb   <- Ruby extension source
+    |
+    +- src/
+    |   |
+    |   +- example.c    <- C extension source
+    |
+    +- test/
+    |   |
+    |   +- example.rb   <- Test code for C and Ruby extension
+    |
+    +- mrbgem.rake      <- GEM specification
+```
 
 ## Binary gems
 
@@ -389,23 +395,23 @@ binary gems, to separate normal gems and binary gems.
 ### Example
 
 ```
- +- mruby-bin-example/
++- mruby-bin-example/
     |
-    +- README.md         (Optional)
+    +- README.md        (Optional)
     |
     +- bintest/
-    |  |
-    |  +- example.rb     <- Test code for binary gem
+    |   |
+    |   +- example.rb   <- Test code for binary gem
     |
-    +- mrbgem.rake       <- Gem specification
+    +- mrbgem.rake      <- Gem specification
     |
-    +- mrblib/           <- Source for Ruby extension (Optional)
+    +- mrblib/          <- Source for Ruby extension (Optional)
     |
-    +- src/              <- Source for C extension (Optional)
+    +- src/             <- Source for C extension (Optional)
     |
     +- tools/
-       |
-       +- example/       <- Executable name directory
-       |
-       +- example.c	 <- Source for Executable (includes main)
+        |
+        +- example/     <- Executable name directory
+        |
+        +- example.c    <- Source for Executable (includes main)
 ```