Document for wal_log_hints

Hi,

When I read the document for wal_log_hints, I see:

<para>
If data checksums are enabled, hint bit updates are always WAL-logged
and this setting is ignored. You can use this setting to test how much
extra WAL-logging would occur if your database had data checksums
enabled.
</para>

I think if it should be changed to ".. if your database had data
checksums *disabled*".

Per my check, wal_log_hints is not used except the case:

#define XLogHintBitIsNeeded() (DataChecksumsEnabled() || wal_log_hints)

So if data checksums is enabled, nothing can be tested when turning
wal_log_hints on/off.

--
Best Regards
Andy Fan