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  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 
Reviewed-by: Jelte Fennema-Nio 
Discussion: https://postgr.es/m/202401301236[email protected]