Two small doc fixes for config.sgml

Hi,

I found two small issues in config.sgml and attached patches for both.

#1
The documentation for jit_debugging_support and jit_profiling_support says
these parameters can only be set at server start. However, both use
the PGC_SU_BACKEND context, which means they can be set at session start
by superusers or users with the appropriate SET privilege, but cannot be
changed within an active session. So, these descriptions should be corrected.
This fix should be backpatched to all supported versions.

#2
config.sgml describes the io_max_workers, io_worker_idle_timeout,
and io_worker_launch_interval GUCs as type "int". Elsewhere, config.sgml
consistently uses "integer" for this type. So those descriptions should be
updated to use "integer" for consistency.

Regards,

--
Fujii Masao