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