[pgpool-committers: 5102] pgpool: Add "Migration to Version 4.0" section to releasenote.

[Bo Peng]

Add "Migration to Version 4.0" section to releasenote.

Branch
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master

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=3cc331f8aac26d71740ce4340903cadcb1731997

Modified Files
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doc/src/sgml/release-4.0.sgml | 143 ++++++++++++++++++++++++++++++++----------
1 file changed, 111 insertions(+), 32 deletions(-)