doc/rados: correct "full ratio" note

Correct a note that directed users not to add an OSD after the cluster
has reached its "full ratio". The note now says "Do not let your cluster
reach its full ratio before adding an OSD."

Hat tip: Oskar Berggren

Fixes: https://tracker.ceph.com/issues/68900

Co-authored-by: Oskar Berggren <[email protected]>
Signed-off-by: Zac Dover <[email protected]>

Author: zdover23

doc/rados/operations/add-or-rm-osds.rst

@@ -17,8 +17,8 @@ It's a good idea to check the capacity of your cluster so that you know when it
 approaches its capacity limits. If your cluster has reached its ``near full``
 ratio, then you should add OSDs to expand your cluster's capacity.
 
-.. warning:: Do not add an OSD after your cluster has reached its ``full
-   ratio``. OSD failures that occur after the cluster reaches its ``near full
+.. warning:: Do not let your cluster reach its ``full ratio`` before adding an
+   OSD. OSD failures that occur after the cluster reaches its ``near full
    ratio`` might cause the cluster to exceed its ``full ratio``.