pgsql: Adjust libpq docs to be clearer about 'hostaddr' usage by reword

Adjust libpq docs to be clearer about 'hostaddr' usage by rewording and
using an itemized list.

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=5ed45ac09c604555740e7365a722b641f3bce498

Modified Files
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doc/src/sgml/libpq.sgml | 46 ++++++++++++++++++++++++++++++----------------
1 files changed, 30 insertions(+), 16 deletions(-)