[Debian-astro-maintainers] Bug#983152: Put alternative warnings in package Description

[積丹尼 Dan Jacobson]

Package: python3-ephem
Version: 3.7.7.1-1+b3
File: /usr/lib/python3/dist-packages/ephem/doc/index.rst

We read in this file warnings that the user should use Two Alternatives.
OK perhaps mention that in the Package Description, lest the user become
highly invested in this package, great as it may be, before learning
that it has been superseded.