Adding a note to protocol.sgml regarding CopyData

In libpq.sgml following is stated:

Before <productname>PostgreSQL</productname> protocol 3.0, it was necessary
for the application to explicitly send the two characters
<literal>\.</literal> as a final line to indicate to the server that it had
finished sending <command>COPY</command> data. While this still works, it is deprecated and the
special meaning of <literal>\.</literal> can be expected to be removed in a
future release. It is sufficient to call <function>PQendcopy</function> after
having sent the actual data.

I think this should be mentioned in protocol.sgml as well. Developers
who wish to develop programs that understand frontend/backend protocol
should be able to focus on protocol.sgml. Attached is a patch for
this.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp