Documentation changes get =items, not =head3s.
Additionally, the following selected changes have been made:
-=head3 L<perldiag/Variable length lookbehind not implemented in regex m/%s/>
+=over 4
+
+=item * L<perldiag/Variable length lookbehind not implemented in regex m/%s/>
This now gives more ideas as to workarounds to the issue that was
introduced in Perl 5.18 (but not documented explicitly in its perldelta)
to be considered variable length, and hence disallowed.
-=over 4
-
=item *
The section on reference counting in L<perlguts> has been heavily revised,