btrfs-progs: docs: add notes about interruption to scrub/dev-replace

Since the kernel patch is queued for v6.19, add notes to scrub and
dev-replace about the new behavior change.

For scrub it's not a huge deal as we can just resume using 'btrfs scrub
resume' command.
But for dev-replace one has to start from the beginning, thus it's
recommended to disable pm during dev-replace.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

Documentation/btrfs-replace.rst

@@ -37,6 +37,18 @@ start [options] <srcdev>|<devid> <targetdev> <path>
                 larger target device; this can be achieved with
                 ``btrfs filesystem resize <devid>:max /path``
 
+	.. note::
+		Device replace can be interrupted by various events after v6.19 kernel,
+		including but not limited to power management suspend/hibernate,
+		filesystem freezing, cgroup freezing (utilized by systemd for slice freezing)
+		and pending signals.
+
+		The running device replace will be cancelled after such interruption, and
+		the end user needs to restart the device replace from the beginning.
+
+		Thus it's recommended to inhibit suspend/hiberate before executing the
+		device replace operation.
+
         ``Options``
 
         -r

Documentation/ch-scrub-intro.rst

@@ -56,6 +56,14 @@ read-write mounted filesystem.
    To avoid any writes from scrub, one has to run read-only scrub on read-only
    filesystem.
 
+.. note::
+   Scrub can be interrupted by various events after v6.19 kernel, including
+   but not limited to power management suspend/hibernate, filesystem freezing,
+   cgroup freezing (utilized by systemd for slice freezing) and pending signals.
+
+   The running scrub will be cancelled after such interruption, and can be resumed
+   by :command:`btrfs scrub resume` command.
+
 The user is supposed to run it manually or via a periodic system service. The
 recommended period is a month but it could be less. The estimated device bandwidth
 utilization is about 80% on an idle filesystem.