[pgpool-committers: 5059] pgpool: Add Pgpool-II 4.0 release note.

[Bo Peng]

Add Pgpool-II 4.0 release note.

Branch
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master

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=88ebfda227f09ed152caa264e79dae0a88e928f7

Modified Files
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doc/src/sgml/filelist.sgml    |   1 +
doc/src/sgml/release-4.0.sgml | 474 ++++++++++++++++++++++++++++++++++++++++++
doc/src/sgml/release.sgml     |   1 +
3 files changed, 476 insertions(+)