Obsolete advocacy for E-style strings in regexp documentation

func.sgml has this bit near line 4660:

   <note>
    <para>
     Keep in mind that an escape's leading <literal>\</> will need to be
     doubled when entering the pattern as an SQL string constant.  For example:
<programlisting>
'123' ~ E'^\\d{3}' <lineannotation>true</lineannotation>
</programlisting>
    </para>
   </note>

This advice was surely helpful when it was written, but nowadays it's just
advocating use of gratuitously non-SQL-standard string literal syntax.
I propose just deleting the whole <note> in HEAD, and maybe 9.5 too.

A more aggressive approach would be to get rid of use of E-style literals
in all/most of the documentation examples.  I'm *not* advocating that,
at least not yet.  But this particular bit seems to be going out of its
way to give obsolete advice.

Thoughts?

            regards, tom lane