Structure of documentation pages created.

The content of the pages comes from the project's README file, written
in Markdown.

The main layout of the page is defined in the _layouts/page.html
file. Jekyll should take care of the conversion and wrapping.

Styles need to be properly defined.
Started to improve layout using Bootstrap.

Home and other pages on a different layout.
Improved all styles: home page and others

Still some hiccups, in particular:
- kind of broken when viewport width is too small
- links and menu need to be revisited
- background image hidden by footer, need to go besides it

Most of the styles taken from Bootstrap to speed up things.
Layout adjusted for different viewports widths
Added section anchors and fixed all cross-pages links