Remove incorrect instructions to run CREATE FOREIGN DATA WRAPPER

The CREATE EXTENSION step does this automatically. Doing it again will
cause an error.

doc/src/sgml/file-fdw.sgml

@@ -173,14 +173,6 @@
 CREATE EXTENSION file_fdw;
 </programlisting>
 
-  <para>
-   Next, create the foreign data wrapper:
-
-<programlisting>
-CREATE FOREIGN DATA WRAPPER file_fdw HANDLER file_fdw_handler;
-</programlisting>
-  </para>
-
   <para>
    Then create a foreign data server: