pgsql: Note that sslmode=require verifies the CA if root cert is presen

Note that sslmode=require verifies the CA if root cert is present

This mode still exists for backwards compatibility, making
sslmode=require the same as sslmode=verify-ca when the file is present,
but not causing an error when it isn't.

Per bug 6189, reported by Srinivas Aji

Branch
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REL9_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/2b250fb077a15790c6fc1e12b981330ed007e66d

Modified Files
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doc/src/sgml/libpq.sgml |   16 +++++++++++++++-
1 files changed, 15 insertions(+), 1 deletions(-)