alembic: Database updates required.

alembic: Database updates required.

This commit doesn't actually change anything.  It just adds the following
upgrade notes that were omitted from the original commits.

Resolves: #1097

UpgradeNote: Two commits in this release...
'Add SHA-256 and SHA-512-256 as authentication digest algorithms'
'res_pjsip: Add new AOR option "qualify_2xx_only"'
...have modified alembic scripts for the following database tables: ps_aors,
ps_contacts, ps_auths, ps_globals. If you don't use the scripts to update
your database, reads from those tables will succeeed but inserts into the
ps_contacts table by res_pjsip_registrar will fail.