[pgpool-committers: 8611] pgpool: Doc: add release notes.

[Bo Peng]

Doc: add release notes.

Branch
------
V4_0_STABLE

Details
-------
https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=a74c35a0b6611dc1a4988f79617eac04e500e444

Modified Files
--------------
doc.ja/src/sgml/release-3.7.sgml | 142 ++++++++++++++++++++++++++++++
doc.ja/src/sgml/release-4.0.sgml | 179 ++++++++++++++++++++++++++++++++++++++
doc/src/sgml/release-3.7.sgml    | 143 +++++++++++++++++++++++++++++++
doc/src/sgml/release-4.0.sgml    | 180 +++++++++++++++++++++++++++++++++++++++
4 files changed, 644 insertions(+)