Syntax highlighting in Jekyll Bootstrap

This is a very detailed guide on how to add syntax highlighting in Jekyll (Github Pages). Basically, rouge will slice the codes accordingly into separate HTML tags, the css will color it according to your theme. kramdown is the Markdown processor supported in Github Pages. What I did on my Jekyll Bootstrap:

Install rouge and kramdown to generate css and render locally in the same manner as Github Pages.
```
 gem install kramdown rouge
```

Update _config.yml

 markdown: kramdown
 highlighter: rouge
 kramdown:
   input: GFM #Github Flavored Markdown
   hard_wrap: false  
   syntax_highlighter: rouge

Create css file to color the syntax. I use the Bootstrap-3 theme.

 rougify style monokai > assets/themes/bootstrap-3/css/syntax.css

Add css link in <head> in _includes/themes/bootstrap-3/default.html.
```
 <link href="/css/syntax.css" rel="stylesheet">  
```

Jekyll 3.3.1 did not render the indented code block for numbered lists correctly. When I did bundle update and was updated to jekyll 3.4.3, it showed up fine.