- remove gnats reference from docproj
- update url for bug listing

Differential Revision:	https://reviews.freebsd.org/D1219
Approved by:	remko (mentor)


git-svn-id: svn+ssh://svn.freebsd.org/doc/head@46024 c2e8774f-c49f-e111-b436-862b2bbc8956