Doc necessity for superuser privileges to execute pg_import_system_collations()

[torikoshia]

Hi.

It seems that only superusers can execute pg_import_system_collations(), 
but this is not mentioned in the manual.

Since other functions that require superuser privileges describe that in 
the manual, I think it would be better to do the same for consistency.

Thoughts?

--
Regards,

--
Atsushi Torikoshi
NTT DATA CORPORATIONdiff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index ac6347a971..819f2c8914 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -26563,6 +26563,7 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
         be <literal>pg_catalog</literal>, but that is not a requirement; the
         collations could be installed into some other schema as well.  The
         function returns the number of new collation objects it created.
+        This function is restricted to superusers.
        </para></entry>
       </row>
      </tbody>