Merge branch 'stable-2.10'

* stable-2.10:
  Update 2.10 release notes with info from 2.9.2
  Use US spelling in 2.9.2 release notes
  Release notes for Gerrit 2.9.2
  postgres: fix PK drop, don't assume PK name as TABLE_pkey

Conflicts:
	gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/UpdatePrimaryKeys.java

Change-Id: Ifd82c53e9a4f1e299b883c6eac051f8efcec44aa