0623c5b8ea03f586c3ca904527fd4edeaa3d864a

The flag is given incorrectly as --recheck-mergeability in the schema update instructions. Also add a bullet mentioning the new flag in the release notes body. Change-Id: I55c2c6cb0659e7e439da6878f722520e04270e7d
Description
RETIRED, Gerrit as used by OpenStack