pgsql: Add compatibility note about grant options on GRANT reference pa

Add compatibility note about grant options on GRANT reference page

Point out in the compatibility section that granting grant options to
PUBLIC is not supported by PostgreSQL.  This is already mentioned
earlier, but since it concerns the information schema, it might be
worth pointing out explicitly as a compatibility issue.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/743ed082accbc542294a4408e2e45a6ffb8ec966

Modified Files
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doc/src/sgml/ref/grant.sgml |    6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)