Add Standard-Dialect-5-Minutes md version

A markdown version of the "Standard Dialect in 5 Minutes" article. The translation process goes like this:

1. Clean the HTML layout stuff
2. Remove spurious white spaces
3. Replace some HTML tags
  1. `kbd` -> `code`
  2. `script` (src syntax highlighting stuff) -> `pre`
4. Escape `pre` tags HTML content
5. Transform the HTML into MD using pandoc
6. Tag each code block in the MD source with the right language

Given step 6 is a manual process, I can't automate the whole thing, so translating the rest of the articles will take some time :)

@ultraq, could you please take a look at the markdown source and tell me if you see any problem? Thx!