Fix room_list_publication_rules docs for v1.126.0 (#18286)

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

changelog.d/18286.doc

@@ -0,0 +1 @@
+Update `room_list_publication_rules` docs to consider defaults that changed in v1.126.0. Contributed by @HarHarLinks.

docs/usage/configuration/config_documentation.md

@@ -4331,23 +4331,11 @@ room list by default_
 Example configuration:
 
 ```yaml
-# No rule list specified. Anyone may publish any room to the public list.
+# No rule list specified. No one may publish any room to the public list, except server admins.
 # This is the default behaviour.
 room_list_publication_rules:
 ```
 
-```yaml
-# A list of one rule which allows everything.
-# This has the same effect as the previous example.
-room_list_publication_rules:
-  - "action": "allow"
-```
-
-```yaml
-# An empty list of rules. No-one may publish to the room list.
-room_list_publication_rules: []
-```
-
 ```yaml
 # A list of one rule which denies everything.
 # This has the same effect as the previous example.
@@ -4355,6 +4343,19 @@ room_list_publication_rules:
   - "action": "deny"
 ```
 
+```yaml
+# An empty list of rules.
+# This has the same effect as the previous example.
+room_list_publication_rules: []
+```
+
+```yaml
+# A list of one rule which allows everything.
+# This was the default behaviour pre v1.126.0.
+room_list_publication_rules:
+  - "action": "allow"
+```
+
 ```yaml
 # Prevent a specific user from publishing rooms.
 # Allow other users to publish anything.