doc: restore wording from recent patch "rolled back to"

bmomjian · bmomjian · commit f0862643ee6b · 2020-03-31T17:52:48.000-04:00
Reported-by: Tom Lane Discussion: https://postgr.es/m/31072.1585690490@sss.pgh.pa.us Backpatch-through: 9.5 - 12
diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml
@@ -1041,7 +1041,7 @@ ERROR:  could not serialize access due to read/write dependencies among transact
    <para>
     Once acquired, a lock is normally held until the end of the transaction.  But if a
     lock is acquired after establishing a savepoint, the lock is released
-    immediately if the savepoint is rolled back.  This is consistent with
+    immediately if the savepoint is rolled back to.  This is consistent with
     the principle that <command>ROLLBACK</command> cancels all effects of the
     commands since the savepoint.  The same holds for locks acquired within a
     <application>PL/pgSQL</application> exception block: an error escape from the block
