Thread: pgsql: doc: Update RFC URLs

doc: Update RFC URLs

Consistently use the IETF HTML links instead of a random mix of
different sites and formats.  This also fixes one broken link for JSON
documentation.

Branch
------
REL9_6_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/feb4b80388696a3493044c4ea8554e41f8548a85

Modified Files
--------------
doc/src/sgml/json.sgml     | 2 +-
doc/src/sgml/libpq.sgml    | 2 +-
doc/src/sgml/pgcrypto.sgml | 6 +++---
3 files changed, 5 insertions(+), 5 deletions(-)