Thread: pgsql: Doc: extend warnings about collation-mismatch hazards in postgre

Doc: extend warnings about collation-mismatch hazards in postgres_fdw.

Be a little more vocal about the risks of remote collations not
matching local ones.  Actually fixing these risks seems hard,
and I've given up on the idea that it might be back-patchable.
So the best we can do for the back branches is add documentation.

Per discussion of bug #16583 from Jiří Fejfar.

Discussion: https://postgr.es/m/2438715.1632510693@sss.pgh.pa.us

Branch
------
REL_10_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/1d7e8e772453a4edd99b3954a9f3707ce5a2176a

Modified Files
--------------
doc/src/sgml/postgres-fdw.sgml | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)