scram_iterations is undocumented GUC_REPORT

I noticed while answering a question that commit b577743000cd added the
GUC scram_iterations and marked it GUC_REPORT, but failed to add it to
the PQparameterStatus documentation.

Here's a proposed patch to add it there.

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index d0d5aefadc..13bd82efc6 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -2521,7 +2521,8 @@ const char *PQparameterStatus(const PGconn *conn, const char *paramName);
<varname>DateStyle</varname>,
<varname>IntervalStyle</varname>,
<varname>TimeZone</varname>,
- <varname>integer_datetimes</varname>, and
+ <varname>integer_datetimes</varname>,
+ <varname>scram_iterations</varname>, and
<varname>standard_conforming_strings</varname>.
(<varname>server_encoding</varname>, <varname>TimeZone</varname>, and
<varname>integer_datetimes</varname> were not reported by releases before 8.0;

Further thoughts:

1. that list looks to be in random order. Should we sort it
alphabetically?

2. the notes about the versions in which some parameters started to be
reported, look quite outdated. We don't really care about things not
reported in 8.0 or 8.1 or even 9.0. For all purposes, it seems
perfectly OK to say that these parameters have been reported forever
(i.e. don't mention them in these lists). I think we should remove all
those, except the note about version 14.

3. Should we list scram_iterations as having started to be reported with
version 16? The GUC didn't exist before that; but we could say that if
it's not reported, then the application can assume that the value is
4096 (similar to the wording for standard_conforming_strings).

Thanks

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
"Los cuentos de hadas no dan al niño su primera idea sobre los monstruos.
Lo que le dan es su primera idea de la posible derrota del monstruo."
(G. K. Chesterton)