pgsql: Doc: remove ancient comment.

Doc: remove ancient comment.

There's a very old comment in rules.sgml added back to 2003. It
expected to a feature coming back but it never happened. So now we can
safely remove the comment. Back-patched to all supported branches.

Discussion: /messages/by-id/20190211.191004.219630835457494660.t-ishii@sraoss.co.jp

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/6e5c270318c92bdb1689da45304d27f85aeb0b91

Modified Files
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doc/src/sgml/rules.sgml | 24 ------------------------
1 file changed, 24 deletions(-)