Bug#809690: mention where to send bug reports on the man page

[積丹尼 Dan Jacobson]

>>>>> "SC" == Sebastiaan Couwenberg <sebastic at xs4all.nl> writes:

SC> The location of the upstream bug tracker is documented in the upstream
SC> metadata file included in the proj source package:

SC> https://anonscm.debian.org/cgit/pkg-grass/proj.git/tree/debian/upstream/metadata

OK but I don't think that file makes it into much of what regular (non
source) users see.

At least comparing to e.g., GNU cat where where to report bugs is on the
man and Info pages...