[pgpool-committers: 7348] pgpool: Doc: add 4.2.1 release note.

[Bo Peng]

Doc: add 4.2.1 release note.

Branch
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V4_2_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=00afb7068181f6fee4d54460a367fc4abd2847f0

Modified Files
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doc.ja/src/sgml/release-4.2.sgml | 151 +++++++++++++++++++++++++++++++++++++++
doc/src/sgml/release-4.2.sgml    | 138 +++++++++++++++++++++++++++++++++++
2 files changed, 289 insertions(+)