Versions view on docs

[hermanzdosilovic]

Show only last 10 versions on left margin but links to older than 10 versions should still work.

Add instructions on how to visit and see docs for older versions in FAQ.

Alternatively versions collapse in "View more..." but show only last 10 versions.

[ijelacicbot]

Opened #47 to limit the docs version sidebar to the last 10 versions and add FAQ instructions for older docs.