Advise project maintainers on Project Links (#3169)
Advise project maintainers on Project Links (#3169)

Add help text in Project Settings (where maintainers would
naturally look for it) telling them how to update the Project
Links sidebar using fields in setup.py.

Fixes #3119.
dstufft/warehouse,pypa/warehouse,pypa/warehouse,dstufft/warehouse,dstufft/warehouse,pypa/warehouse,dstufft/warehouse,pypa/warehouse