pgsql: Update PQparameterStatus and ParameterStatus docs

Update PQparameterStatus and ParameterStatus docs

Cover scram_iterations, which was added in commit b577743000cd. While
at it, turn the list into a <simplelist> with 2 columns, which is much
nicer to read.

In master, remove mentions of antediluvian versions before which some
parameters were not reported.

Noticed while investigating a question by Maiquel Grassi.

Backpatch to 16.

Reviewed-by: Daniel Gustafsson <daniel(at)yesql(dot)se>
Reviewed-by: Jelte Fennema-Nio <postgres(at)jeltef(dot)nl>
Discussion: https://postgr.es/m/202401301236.mc5ebrohhtsd@alvherre.pgsql

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/a39f1a365a3b99149ba0038ef7e39d6bff2560c9

Modified Files
--------------
doc/src/sgml/libpq.sgml | 43 ++++++++++++++++++++-----------------------
doc/src/sgml/protocol.sgml | 43 ++++++++++++++++++++-----------------------
2 files changed, 40 insertions(+), 46 deletions(-)