perlref.pod: Fix heading levels and ordering

Commit cb1a09d0194fed9b905df7b04a4bc031d354609d (perl 5.002) promoted
the WARNING and SEE ALSO headings in perlref from `=head2` to
`=head1`, but subsequent changes added things that should have been
`=head2` before the WARNING as `=head1` between the two.

Commit f0d9913136619e8b6716f2dfa6d8524a6df9e2c0 fixed some of those
heading levels, but left "Declaring a Reference to a Variable" as
`=head1`.

1 files changed, 21 insertions, 21 deletions

diff --git a/pod/perlref.pod b/pod/perlref.pod
index 2c4cedfe64..5cd9ee21f8 100644
--- a/pod/perlref.pod
+++ b/pod/perlref.pod
@@ -712,26 +712,6 @@ outer() at the time outer is invoked.
 This has the interesting effect of creating a function local to another
 function, something not normally supported in Perl.
 
-=head1 WARNING: Don't use references as hash keys
-X<reference, string context> X<reference, use as hash key>
-
-You may not (usefully) use a reference as the key to a hash.  It will be
-converted into a string:
-
-    $x{ \$a } = $a;
-
-If you try to dereference the key, it won't do a hard dereference, and
-you won't accomplish what you're attempting.  You might want to do something
-more like
-
-    $r = \@a;
-    $x{ $r } = $r;
-
-And then at least you can use the values(), which will be
-real refs, instead of the keys(), which won't.
-
-The standard Tie::RefHash module provides a convenient workaround to this.
-
 =head2 Postfix Dereference Syntax
 
 Beginning in v5.20.0, a postfix syntax for using references is
@@ -903,7 +883,7 @@ will only be visible within that inner sub, and will not affect the outer
 subroutine where the variables are declared.  This bizarre behavior is
 subject to change.
 
-=head1 Declaring a Reference to a Variable
+=head2 Declaring a Reference to a Variable
 
 Beginning in v5.26.0, the referencing operator can come after C<my>,
 C<state>, C<our>, or C<local>.  This syntax must be enabled with C<use
@@ -926,6 +906,26 @@ used on just some items in a list of declared variables:
 
     my ($foo, \@bar, \%baz); # equivalent to:  my $foo, \my(@bar, %baz);
 
+=head1 WARNING: Don't use references as hash keys
+X<reference, string context> X<reference, use as hash key>
+
+You may not (usefully) use a reference as the key to a hash.  It will be
+converted into a string:
+
+    $x{ \$a } = $a;
+
+If you try to dereference the key, it won't do a hard dereference, and
+you won't accomplish what you're attempting.  You might want to do something
+more like
+
+    $r = \@a;
+    $x{ $r } = $r;
+
+And then at least you can use the values(), which will be
+real refs, instead of the keys(), which won't.
+
+The standard Tie::RefHash module provides a convenient workaround to this.
+
 =head1 SEE ALSO
 
 Besides the obvious documents, source code can be instructive.