Deploy multiversion docs at https://nest.nitk.ac.in/docs

. Add a
index.html file to redirect to the latest released version docs.

Trigger "test docs" and "release docs" jobs on changes in docs/ folder
and any sub-directories.

Add information in CONTRIBUTING.md regarding when style violations
will be informed to the user.

Signed-off-by: Shanthanu S Rai <shanthanu.s.rai9@gmail.com>