[pgpool-committers: 7234] pgpool: Doc: add release note.

[Bo Peng]

Doc: add release note.

Branch
------
V3_7_STABLE

Details
-------
https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=33cf7a19d459995ef1a73141d407b9504d25bfe9

Modified Files
--------------
doc.ja/src/sgml/release-3.5.sgml | 73 ++++++++++++++++++++++++++++++++
doc.ja/src/sgml/release-3.6.sgml | 82 ++++++++++++++++++++++++++++++++++++
doc.ja/src/sgml/release-3.7.sgml | 91 ++++++++++++++++++++++++++++++++++++++++
doc/src/sgml/release-3.5.sgml    | 60 ++++++++++++++++++++++++++
doc/src/sgml/release-3.6.sgml    | 69 ++++++++++++++++++++++++++++++
doc/src/sgml/release-3.7.sgml    | 78 ++++++++++++++++++++++++++++++++++
6 files changed, 453 insertions(+)