Fix docs on resetting the user directory (#5036)

Signed-off-by: Aaron Raimist <aaron@raim.ist>

docs/user_directory.md

@@ -7,11 +7,7 @@ who are present in a publicly viewable room present on the server.
 
 The directory info is stored in various tables, which can (typically after
 DB corruption) get stale or out of sync.  If this happens, for now the
-quickest solution to fix it is:
-
-```
-UPDATE user_directory_stream_pos SET stream_id = NULL;
-```
-
-and restart the synapse, which should then start a background task to
+solution to fix it is to execute the SQL here
+https://github.com/matrix-org/synapse/blob/master/synapse/storage/schema/delta/53/user_dir_populate.sql
+and then restart synapse. This should then start a background task to
 flush the current tables and regenerate the directory.

synapse/config/user_directory.py

@@ -43,9 +43,9 @@ class UserDirectoryConfig(Config):
         #
         # 'search_all_users' defines whether to search all users visible to your HS
         # when searching the user directory, rather than limiting to users visible
-        # in public rooms.  Defaults to false.  If you set it True, you'll have to run
-        # UPDATE user_directory_stream_pos SET stream_id = NULL;
-        # on your database to tell it to rebuild the user_directory search indexes.
+        # in public rooms.  Defaults to false.  If you set it True, you'll have to
+        # rebuild the user_directory search indexes, see
+        # https://github.com/matrix-org/synapse/blob/master/docs/user_directory.md
         #
         #user_directory:
         #  enabled: true