Hi!

These patches clean up the OpenPGP nomenclature usage (and some other
minor lateral cleanups, mostly grammar fixes), in package documentation
and in the keyring filenames, while providing backward compatibility
symlinks for the old names so that people can transition easily.

(Ideally I'd have done this by renaming and then adding .links fragments
files, if they for example were signed individually, but given the
SHA512SUMS.txt.asc file, I had to create the symlinks on disk to avoid
breaking the build.)

This should fix multiple pedantic lintian tags. :D

Thanks,
Guillem