Update changelog to better expain password reset change (#5545)

Updates the v1.0.0 changelog to provide more information to those upgrading to v1.0 on why they may receive errors or find their password reset abilities have now been disabled.

Helps address #5444

CHANGES.md

@@ -52,7 +52,11 @@ Features
 - Add a script to generate new signing-key files. ([\#5361](https://github.com/matrix-org/synapse/issues/5361))
 - Update upgrade and installation guides ahead of 1.0. ([\#5371](https://github.com/matrix-org/synapse/issues/5371))
 - Replace the `perspectives` configuration section with `trusted_key_servers`, and make validating the signatures on responses optional (since TLS will do this job for us). ([\#5374](https://github.com/matrix-org/synapse/issues/5374))
-- Add ability to perform password reset via email without trusting the identity server. ([\#5377](https://github.com/matrix-org/synapse/issues/5377))
+- Add ability to perform password reset via email without trusting the identity server. **As a result of this PR, password resets will now be disabled on the default configuration.**
+
+  Password reset emails are now sent from the homeserver by default, instead of the identity server. To enable this functionality, ensure `email` and `public_baseurl` config options are filled out.
+
+  If you would like to re-enable password resets being sent from the identity server (warning: this is dangerous! See [#5345](https://github.com/matrix-org/synapse/pull/5345)), set `email.trust_identity_server_for_password_resets` to true. ([\#5377](https://github.com/matrix-org/synapse/issues/5377))
 - Set default room version to v4. ([\#5379](https://github.com/matrix-org/synapse/issues/5379))
 
 

changelog.d/5545.misc

@@ -0,0 +1 @@
+Update v1.0.0 release changelog to include more information about changes to password resets.