pgsql: docs: ulink all references to RFC's

docs: ulink all references to RFC's

Make sure that the first mentions of RFC's are ulinked to their ietf.org
entry, and subsequent ones are marked as acronyms. This makes references
to RFC's consistent across the documentation.

Author: Daniel Gustafsson
Discussion: https://www.postgresql.org/message-id/2C697878-4D01-4F06-8312-2FEDE931E973%40yesql.se

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/415dc2009683904f337a1837b6b4eb7f31c4dc55

Modified Files
--------------
doc/src/sgml/catalogs.sgml    |  2 +-
doc/src/sgml/charset.sgml     |  2 +-
doc/src/sgml/client-auth.sgml | 19 ++++++++++++-------
doc/src/sgml/datatype.sgml    |  6 ++++--
doc/src/sgml/ecpg.sgml        |  2 +-
doc/src/sgml/func.sgml        |  2 +-
doc/src/sgml/json.sgml        |  4 ++--
doc/src/sgml/libpq.sgml       |  5 +++--
doc/src/sgml/pgcrypto.sgml    |  7 ++++---
doc/src/sgml/protocol.sgml    |  6 ++++--
doc/src/sgml/textsearch.sgml  |  6 +++---
doc/src/sgml/uuid-ossp.sgml   |  5 +++--
12 files changed, 39 insertions(+), 27 deletions(-)