Update index page for docs publication

Update index page for the governance.openstack.org TC docs publication
website, in order to match content from the wiki page.

This will allow to deprecate the "reference" nature of the wiki page and
make it more about the meeting and the process to propose changes.

Change-Id: I7745156d91aa2e1a4b45160bd7f721ce541ab175
Merge "Update index page for docs publication"