Typo fixes.

expect -> except, noted by Andrew Dunstan.  Also, "cannot" seems more
readable here than "can not", per David Wheeler.

doc/src/sgml/func.sgml

@@ -14888,7 +14888,7 @@ SELECT (pg_stat_file('filename')).modification;
    </indexterm>
    <para>
     <function>pg_advisory_xact_lock</> works the same as
-    <function>pg_advisory_lock</>, expect the lock is automatically released
+    <function>pg_advisory_lock</>, except the lock is automatically released
     at the end of the current transaction and cannot be released explicitly.
    </para>
 
@@ -14897,7 +14897,7 @@ SELECT (pg_stat_file('filename')).modification;
    </indexterm>
    <para>
     <function>pg_advisory_xact_lock_shared</> works the same as
-    <function>pg_advisory_lock_shared</>, expect the lock is automatically released
+    <function>pg_advisory_lock_shared</>, except the lock is automatically released
     at the end of the current transaction and cannot be released explicitly.
    </para>
 
@@ -14906,7 +14906,7 @@ SELECT (pg_stat_file('filename')).modification;
    </indexterm>
    <para>
     <function>pg_try_advisory_xact_lock</> works the same as
-    <function>pg_try_advisory_lock</>, expect the lock, if acquired,
+    <function>pg_try_advisory_lock</>, except the lock, if acquired,
     is automatically released at the end of the current transaction and
     cannot be released explicitly.
    </para>
@@ -14916,7 +14916,7 @@ SELECT (pg_stat_file('filename')).modification;
    </indexterm>
    <para>
     <function>pg_try_advisory_xact_lock_shared</> works the same as
-    <function>pg_try_advisory_lock_shared</>, expect the lock, if acquired,
+    <function>pg_try_advisory_lock_shared</>, except the lock, if acquired,
     is automatically released at the end of the current transaction and
     cannot be released explicitly.
    </para>