Correct error in user_directory docs (#17348)

### Pull Request Checklist

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---------

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

1 files changed, 1 insertions, 0 deletions

diff --git a/changelog.d/17348.doc b/changelog.d/17348.doc
new file mode 100644
index 0000000000..4ce42bbadb
--- /dev/null
+++ b/changelog.d/17348.doc
@@ -0,0 +1 @@
+Fix an error in the docs for `search_all_users` parameter under `user_directory`.