Add some notes about recent Jitsi changes

A bit late, but still better than nothing.

CHANGELOG.md

@@ -1,3 +1,18 @@
+# 2020-11-27
+
+## Recent Jitsi updates may require configuration changes
+
+We've recently [updated from Jitsi build 4857 to build 5142](https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/719), which brings a lot of configuration changes.
+
+**If you use our default Jitsi settings, you won't have to do anything.**
+
+People who have [fine-tuned Jitsi](docs/configuring-playbook-jitsi.md#optional-fine-tune-jitsi) may find that some options got renamed now, others are gone and yet others still need to be defined in another way.
+
+The next time you run the playbook [installation](docs/installing.md) command, our validation logic will tell you if you're using some variables like that and will recommend a migration path for each one.
+
+Additionally, we've recently disabled transcriptions (`matrix_jitsi_enable_transcriptions: false`) and recording (`matrix_jitsi_enable_recording: false`) by default. These features did not work anyway, because we don't install the required dependencies for them (Jigasi and Jibri, respectively). If you've been somehow pointing your Jitsi installation to some manually installed Jigasi/Jibri service, you may need to toggle these flags back to enabled to have transcriptions and recordings working.
+
+
 # 2020-11-23
 
 ## Breaking change matrix-sms-bridge