recovery_target_timeline & documentation

Hi,

It seems like this part of the documentation was not updated after changing
the default value of recovery_target_timeline to latest in  v12.

"The default behavior of recovery is to recover along the same timeline
that was current when the base backup was taken. If you wish to recover
into some child timeline (that is, you want to return to some state that
was itself generated after a recovery attempt), you need to specify the
target timeline ID in recovery_target_timeline
<https://www.postgresql.org/docs/13/runtime-config-wal.html#GUC-RECOVERY-TARGET-TIMELINE>.
You cannot recover into timelines that branched off earlier than the base
backup." [1][2]

Here is an attempt to fix that.

regards,
Benoit

[1]
https://www.postgresql.org/docs/13/continuous-archiving.html#BACKUP-TIMELINES
[2]
https://www.postgresql.org/docs/12/continuous-archiving.html#BACKUP-TIMELINES