doc: Mention attribute "inherited" in pg_stats_ext[_exprs]

These have been added in 269b532, but the documentation did not reflect
that.

Author: Noriyoshi Shinoda
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/DM4PR84MB17349C4E7D88A68264C18AF3EED69@DM4PR84MB1734.NAMPRD84.PROD.OUTLOOK.COM

Author: michaelpq

doc/src/sgml/catalogs.sgml

@@ -13408,6 +13408,17 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>inherited</structfield> <type>bool</type>
+       (references <link linkend="catalog-pg-statistic-ext-data"><structname>pg_statistic_ext_data</structname></link>.<structfield>stxdinherit</structfield>)
+      </para>
+      <para>
+       If true, the stats include inheritance child columns, not just the
+       values in the specified relation
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
        <structfield>n_distinct</structfield> <type>pg_ndistinct</type>
@@ -13589,6 +13600,17 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>inherited</structfield> <type>bool</type>
+       (references <link linkend="catalog-pg-statistic-ext-data"><structname>pg_statistic_ext_data</structname></link>.<structfield>stxdinherit</structfield>)
+      </para>
+      <para>
+       If true, the stats include inheritance child columns, not just the
+       values in the specified relation
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
        <structfield>null_frac</structfield> <type>float4</type>