Fix inconsistencies GUC categories

Hi,

It appears that config.sgml and pg_settings have not been updated, even 
though a new subcategory was added in 249d649. a55a984 may have been 
missed in the cleaning.
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Category is 'CONNECTIONS AND AUTHENTICATION' and subcategory is 
'Connection Settings' at config.sgml.
Category is 'CONNECTIONS AND AUTHENTICATION' and subcategory is 
'Connection Settings' at pg_settings.
Category is 'CONNECTIONS AND AUTHENTICATION' and subcategory is 'TCP 
settings' at postgresql.conf.sample.
--

I would like to unify the following with config.sgml as in a55a984.
--
Category is 'REPORTING AND LOGGING' and subcategory is 'PROCESS TITLE' 
at config.sgml.
Category is 'REPORTING AND LOGGING' and subcategory is 'PROCESS TITLE' 
at pg_settings.
Category is 'PROCESS TITLE' and subcategory is none at 
postgresql.conf.sample.
--

Trivial changes were made to the following short_desc.
--
recovery_prefetch
enable_group_by_reordering
stats_fetch_consistency
--

I've attached a patch.
Thoghts?

-- 
Regards,

--
Shinya Kato
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION