Correct error in user_directory docs (#17348)

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---------

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

changelog.d/17348.doc

@@ -0,0 +1 @@
+Fix an error in the docs for `search_all_users` parameter under `user_directory`.

docs/usage/configuration/config_documentation.md

@@ -3807,7 +3807,8 @@ This setting defines options related to the user directory.
 This option has the following sub-options:
 * `enabled`:  Defines whether users can search the user directory. If false then
    empty responses are returned to all queries. Defaults to true.
-* `search_all_users`: Defines whether to search all users visible to your HS at the time the search is performed. If set to true, will return all users who share a room with the user from the homeserver.
+* `search_all_users`: Defines whether to search all users visible to your homeserver at the time the search is performed.
+   If set to true, will return all users known to the homeserver matching the search query.
    If false, search results will only contain users
     visible in public rooms and users sharing a room with the requester.
     Defaults to false.