Restructure examples folder (#47)

Split examples into separate markdown files, each containing a description, sample code, and a screenshot of the resulting xlsx document.

The script `generate.rb` is provided to actually generate the example documents by executing the sample code contained in the markdown files.

1 files changed, 23 insertions, 0 deletions

diff --git a/examples/cached_formula_example.md b/examples/cached_formula_example.md
new file mode 100644
index 00000000..e5b82264
--- /dev/null
+++ b/examples/cached_formula_example.md
@@ -0,0 +1,23 @@
+## Description
+
+When you add a formula in Excel, it immediately calculates its value and store in the document. When you generate an xlsx file, the value is usually empty and it get calculated on the first run. If you want a nice preview with all the data provided, you could add the pre-calculated values
+
+## Code
+
+```ruby
+require 'axlsx'
+
+p = Axlsx::Package.new
+wb = p.workbook
+
+wb.add_worksheet(name: 'Cached formula') do |sheet|
+  sheet.add_row [1, 2, 3]
+  sheet.add_row [1, 2, '=A2+B2'], formula_values: [nil, nil, 3]
+end
+
+p.serialize 'cached_formula_example.xlsx'
+```
+
+## Output
+
+![Output](images/cached_formula_example.png "Output")