Sass: Add Sample Doc to Test CSS Changes

[tajmone]

In assets_src/sass/ we need to add a sample HTML document to quickly test changes to the Sass/CSS stylesheet, without having to also rebuild the docinfo.html file and the actual documents to preview results.

The sample HTML doc should obviously be generated from AsciiDoc sources. So we might include the ADoc source in the folder as well (or in a subfolder maybe).

• [ ] Add a sample HTML document containing all required ALAN code blocks (and whatever custom styles we're defining); this document must import the stylesheet from the current folder (i.e. not embed it) so that by refreshing the HTML page one can see the results of CSS changes:
  • [ ] Add ADoc sources of sample document (in subfolder?).
  • [ ] Add HTML generated sample document.
• [ ] Add a sass watch script? (maybe not needed right now, since there's only one CSS shared by all docs).

[tajmone]

IMPORTANT! — None of the above really matters if we end up reusing the DocInfo file created on ALAN-Docs (see #130).

So we might want to wait and see whether we'll be keeping our own custom Sass/CSS or not.