Clarify changelog entry

CHANGES.md

@@ -1,14 +1,16 @@
 Synapse 1.57.1 (2022-04-20)
 ===========================
 
-This is a patch release that only affects the Docker image. It is only of interest to administrators using the LDAP module to authenticate their users.
+This is a patch release that only affects the Docker image. It is only of interest to administrators using [the LDAP module][LDAPModule] to authenticate their users.
 If you have already upgraded to Synapse 1.57.0 without problem, then you have no need to upgrade to this patch release.
 
+[LDAPModule]: https://github.com/matrix-org/matrix-synapse-ldap3
+
 
 Updates to the Docker image
 ---------------------------
 
-- Include version 0.2.0 of the Synapse LDAP Auth Provider module in the Docker image. ([\#12512](https://github.com/matrix-org/synapse/issues/12512))
+- Include version 0.2.0 of the Synapse LDAP Auth Provider module in the Docker image. This matches the version that was present in the Docker image for Synapse v1.56.0. ([\#12512](https://github.com/matrix-org/synapse/issues/12512))
 
 
 Synapse 1.57.0 (2022-04-19)