feat(CI): add the GitHub Super Linter

The GitHub Super Linter is a more robust and better supported
tool than the current GitHub Actions we are using.

Running these checks:

ERROR_ON_MISSING_EXEC_BIT: true
VALIDATE_BASH: true
VALIDATE_BASH_EXEC: true
VALIDATE_EDITORCONFIG: true
VALIDATE_MARKDOWN: true
VALIDATE_SHELL_SHFMT: true
VALIDATE_YAML: true

https://github.com/marketplace/actions/super-linter
https://github.com/github/super-linter

Added the GitHub Super Linter badge to the README.

Also updated the pre-commit framework and added
more documentation on pre-commit.

Added one more pre-commit check: check-executables-have-shebangs

Added one extra check for merge conflicts to our
GitHub Actions.

EditorConfig and Markdown linting.

Minor grammar and spelling fixes.

Update linter.yml

2 files changed, 2 insertions, 2 deletions

diff --git a/mrbgems/mruby-kernel-ext/src/kernel.c b/mrbgems/mruby-kernel-ext/src/kernel.c
index 2a0ca3a9d..7afa6fa5f 100644
--- a/mrbgems/mruby-kernel-ext/src/kernel.c
+++ b/mrbgems/mruby-kernel-ext/src/kernel.c
@@ -86,7 +86,7 @@ mrb_f_method(mrb_state *mrb, mrb_value self)
  *     Integer(arg,base=0)    -> integer
  *
  *  Converts <i>arg</i> to a <code>Integer</code>.
- *  Numeric types are converted directly (with floating point numbers
+ *  Numeric types are converted directly (with floating-point numbers
  *  being truncated).    <i>base</i> (0, or between 2 and 36) is a base for
  *  integer string representation.  If <i>arg</i> is a <code>String</code>,
  *  when <i>base</i> is omitted or equals to zero, radix indicators
diff --git a/mrbgems/mruby-kernel-ext/test/kernel.rb b/mrbgems/mruby-kernel-ext/test/kernel.rb
index 2ac194dca..fc4402b3d 100644
--- a/mrbgems/mruby-kernel-ext/test/kernel.rb
+++ b/mrbgems/mruby-kernel-ext/test/kernel.rb
@@ -21,7 +21,7 @@ assert('Kernel.caller, Kernel#caller') do
     end
   end
 
-  skip "backtrace isn't available" if(c.new.baz(0)[0].include?("unknown"))
+  skip "backtrace isn't available" if (c.new.baz(0)[0].include?("unknown"))
 
   assert_equal "kernel.rb:#{caller_lineno}:in foo", c.new.baz(0)[0][-19..-1]
   assert_equal "bar", c.new.baz[0][-3..-1]