Add cross links to the plugins section

To do this, we had to move the text where we add the links away from the i18n
string list since Hugo does not support using shortcodes (e.g. for links) in
there.

Also added a new param that points to the docs page that explains our
contribution process (we'll reuse this new param in a later commit for the
development/contributing section of nest)

Testing Done:
Ran dev-server.sh and verified the content looks as intended and links worked

Reviewed at https://reviews.imfreedom.org/r/784/