Return type of txid_status is text, not txid_status

Thinko in commit 857ee8e.

Discovered-by: Gianni Ciolli

Author: alvherre

doc/src/sgml/func.sgml

@@ -17933,7 +17933,7 @@ SELECT collation for ('foo' COLLATE "de_DE");
       </row>
       <row>
        <entry><literal><function>txid_status(<parameter>bigint</parameter>)</function></literal></entry>
-       <entry><type>txid_status</type></entry>
+       <entry><type>text</type></entry>
        <entry>report the status of the given transaction: <literal>committed</literal>, <literal>aborted</literal>, <literal>in progress</literal>, or null if the transaction ID is too old</entry>
       </row>
      </tbody>