pg_default_acl missing 'n' case in doc

[Fabien COELHO]

While looking at ACL prettyprinting, I noticed that "pg_default_acl" 
documentation does not say anything about type 'n' for schema (namespace), 
which seems to be supported according to "\ddp" and the catalog code.

Here is a small addition to add that 'n' is allowed for schema.

--
Fabien.diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index fffb79f713..3bb48d4ccf 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2850,7 +2850,8 @@ SCRAM-SHA-256$<replaceable>&lt;iteration 
count&gt;</replaceable>:<replaceable>&l
        <literal>r</literal> = relation (table, view),
        <literal>S</literal> = sequence,
        <literal>f</literal> = function,
-       <literal>T</literal> = type
+       <literal>T</literal> = type,
+       <literal>n</literal> = schema
       </entry>
      </row>