pgsql: Fix log_temp_files docs and comments to say bytes not kilobytes.

Log Message:
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Fix log_temp_files docs and comments to say bytes not kilobytes.
stat(2) field st_size returns bytes not kilobytes.
Bug found during recent performance tuning for PostgreSQL user.

Modified Files:
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pgsql/doc/src/sgml:
config.sgml (r1.282 -> r1.283)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml?r1=1.282&r2=1.283)
pgsql/src/backend/utils/misc:
guc.c (r1.556 -> r1.557)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c?r1=1.556&r2=1.557)