I have two small patches that you can integrate into your patch set:
The first just changes the punctuation of "Not-null constraints" in the
psql output to match what the documentation mostly uses.
The second has some changes to ddl.sgml to reflect that not-null
constraints are now named and can be operated on like other constraints.
You might want to read that again to make sure it matches your latest
intentions, but I think it catches all the places that are required to
change.