[pgpool-committers: 9372] pgpool: Doc: add release notes.

[Bo Peng]

Doc: add release notes.

Branch
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V4_0_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=97bd9d0530095effc6c241337b4319fbe6d97dd2

Modified Files
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doc.ja/src/sgml/release-4.0.sgml | 338 ++++++++++++++++++++++++++++++++++++
doc/src/sgml/release-4.0.sgml    | 362 +++++++++++++++++++++++++++++++++++++++
2 files changed, 700 insertions(+)