Add changelog entry and make small tweaks

2 jobs for !284 with extra-lemmas in 5 minutes and 13 seconds (queued for 7 seconds)
latest detached
Status Name Job ID Coverage
  Build
passed build-coq.8.10.2 #132564
fp

00:05:12

passed build-coq.8.13.2-mr #132563
fp

00:04:40