Add download and docs links to Gerrit v3.7.0-rc1
Add download and docs links to Gerrit v3.7.0-rc1

The release notes are still empty at the moment, remove
the leftover in the empty template.

Change-Id: Ic90e3d32e1b5529b17c13aca9ca34146d1485b54

GerritCodeReview/homepage,GerritCodeReview/homepage,GerritCodeReview/homepage,GerritCodeReview/homepage,GerritCodeReview/homepage