Clarify what registration_shared_secret allows for (matrix-org#2885)

Signed-off-by: Aaron Raimist <[email protected]>

INSTALL.md

@@ -402,8 +402,8 @@ This process uses a setting `registration_shared_secret` in
 `homeserver.yaml`, which is shared between Synapse itself and the
 `register_new_matrix_user` script. It doesn't matter what it is (a random
 value is generated by `--generate-config`), but it should be kept secret, as
-anyone with knowledge of it can register users on your server even if
-`enable_registration` is `false`.
+anyone with knowledge of it can register users, including admin accounts,
+on your server even if `enable_registration` is `false`.
 
 ## Setting up a TURN server
 

docs/sample_config.yaml

@@ -624,8 +624,8 @@ enable_registration: False
 #  - medium: msisdn
 #    pattern: '\+44'
 
-# If set, allows registration by anyone who also has the shared
-# secret, even if registration is otherwise disabled.
+# If set, allows registration of standard or admin accounts by anyone who
+# has the shared secret, even if registration is otherwise disabled.
 #
 # registration_shared_secret: <PRIVATE STRING>
 

synapse/config/registration.py

@@ -92,8 +92,8 @@ def default_config(self, generate_secrets=False, **kwargs):
         #  - medium: msisdn
         #    pattern: '\\+44'
 
-        # If set, allows registration by anyone who also has the shared
-        # secret, even if registration is otherwise disabled.
+        # If set, allows registration of standard or admin accounts by anyone who
+        # has the shared secret, even if registration is otherwise disabled.
         #
         %(registration_shared_secret)s