Clean up release-process.md after OS X gitian changes
Clean up release-process.md after OS X gitian changes

This is PR #4271, but with the changes to the descriptors, both the names of the
files and the names of the intermediate build artifact archives, removed.
This also closes #3775 if it goes in, because it covers the changes in
that PR.

wastholm/bitcoin,wastholm/bitcoin,wastholm/bitcoin,wastholm/bitcoin,wastholm/bitcoin,wastholm/bitcoin