Added note that _purge is restricted to admin users

https://docs.couchdb.org/en/stable/whatsnew/2.3.html#bugfixes

Author: jesperhoy

src/docs/src/api/database/misc.rst

@@ -131,6 +131,10 @@ As a result of this purge operation, a new updated version of the document will
 be available in ``_all_docs`` and ``_changes``, creating a new record in ``_changes``.
 The database's ``purge_seq`` and ``update_seq`` will be increased.
 
+.. note::
+    The _purge endpoint is restricted to admin users (since version 2.3.1)
+
+
 Internal Replication
 ======================
 Purges are automatically replicated between replicas of the same database. Each