pgsql: Complete the documentation of the USAGE privilege for foreign se

Complete the documentation of the USAGE privilege for foreign servers

The GRANT reference page failed to mention that the USAGE privilege
allows modifying associated user mappings, although this was already
documented on the CREATE/ALTER/DROP USER MAPPING pages.

Branch
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REL8_4_STABLE

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=d833f42eeb6767800b95c2f3e4fb781071ed1c69

Modified Files
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doc/src/sgml/ref/grant.sgml | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)