Update pageinspect.sgml

changed some "-"  to "-&minus"

Author: chegong18

postgresql/doc/src/sgml/pageinspect.sgml

@@ -544,7 +544,7 @@ ____________________________________________________________________________-->
       index's metapage.  For example:
 <screen>
 test=# SELECT * FROM bt_metap('pg_cast_oid_index');
--[ RECORD 1 ]-------------+-------
+-[ RECORD 1 ]-&minus;-&minus;-&minus;-&minus;-&minus;-+-&minus;-&minus;-&minus;-
 magic                     | 340322
 version                   | 4
 root                      | 1
@@ -599,7 +599,7 @@ ____________________________________________________________________________-->
       single pages of B-tree indexes.  For example:
 <screen>
 test=# SELECT * FROM bt_page_stats('pg_cast_oid_index', 1);
--[ RECORD 1 ]-+-----
+-[ RECORD 1 ]-+-&minus;-&minus;-
 blkno         | 1
 type          | l
 live_items    | 224
@@ -1599,4 +1599,4 @@ mapp      | {65}
   </variablelist>
  </sect2>
 
-</sect1>
+</sect1>