Reverse proxies are not the only thing to change;be explicit w/ new endpoint

Author: anoadragon453

CHANGES.md

@@ -7,9 +7,8 @@ As [noted in
 v1.20.0](https://github.com/matrix-org/synapse/blob/release-v1.21.0/CHANGES.md#synapse-1200-2020-09-22),
 a future release will drop support for accessing Synapse's
 [Admin API](https://github.com/matrix-org/synapse/tree/master/docs/admin_api) under the
-`/_matrix/client/*` endpoint prefixes. Please update your
-[reverse proxy configuration](https://github.com/matrix-org/synapse/blob/master/docs/reverse_proxy.md)
-accordingly.
+`/_matrix/client/*` endpoint prefixes. At that point, the Admin API will only
+be accessible under `/_synapse/admin`.
 
 
 Synapse 1.21.0rc3 (2020-10-08)
@@ -168,9 +167,11 @@ API](https://github.com/matrix-org/synapse/tree/master/docs) has been
 accessible under the `/_matrix/client/api/v1/admin`,
 `/_matrix/client/unstable/admin`, `/_matrix/client/r0/admin` and
 `/_synapse/admin` prefixes. In a future release, we will be dropping support
-for accessing Synapse's Admin API using the `/_matrix/client/*` prefixes. This
-makes it easier for homeserver admins to lock down external access to the Admin
-API endpoints.
+for accessing Synapse's Admin API using the `/_matrix/client/*` prefixes.
+
+From that point, the Admin API will only be accessible under `/_synapse/admin`.
+This makes it easier for homeserver admins to lock down external access to the
+Admin API endpoints.
 
 Synapse 1.20.0rc5 (2020-09-18)
 ==============================