doc: add docs and update release notes for the new config option

Fixes: https://tracker.ceph.com/issues/71494

Signed-off-by: Shraddha Agrawal <[email protected]>
(cherry picked from commit 80c7492)

Author: shraddhaag

PendingReleaseNotes

@@ -151,7 +151,8 @@
   users to view the availability score for each pool in a cluster. A pool is considered 
   unavailable if any PG in the pool is not in active state or if there are unfound 
   objects. Otherwise the pool is considered available. The score is updated every 
-  5 seconds. This feature is in tech preview. 
+  5 seconds. The feature is on by default. A new config option `enable_availability_tracking`
+  can be used to turn off the feature if required. This feature is in tech preview. 
   Related trackers:
    - https://tracker.ceph.com/issues/67777
 

doc/rados/configuration/mon-config-ref.rst

@@ -627,6 +627,7 @@ Miscellaneous
 .. confval:: mon_osd_cache_size_min
 .. confval:: mon_memory_target
 .. confval:: mon_memory_autotune
+.. confval:: enable_availability_tracking
 
 .. _Paxos: https://en.wikipedia.org/wiki/Paxos_(computer_science)
 .. _Monitor Keyrings: ../../../dev/mon-bootstrap#secret-keys

doc/rados/operations/monitoring.rst

@@ -784,4 +784,14 @@ the ratio of MTBF to the total time.
 The score is updated every five seconds. This interval is currently 
 not configurable. Any intermittent changes to the pools that 
 occur between this duration but are reset before we recheck the pool 
-status will not be captured by this feature. 
+status will not be captured by this feature. 
+
+This feature is on by default. To turn the feature off, e.g. - for an expected 
+downtime, the ``enable_availability_tracking`` config option can be set to ``false``. 
+
+.. prompt:: bash $
+
+   ceph config set mon enable_availability_tracking false
+
+While the feature is turned off, the last calculated score will be preserved. The 
+score will again start updating once the feature is turned on again.