docs: note that changing encryption option settings for existing clus…

…ters is not dangerous

We have prohibited changing all network-related configurations after cluster creation.
However, as a result of rook#13584, we found that
the connections.encryption flag can be regarded as an exception.

Signed-off-by: ESASHIKA Kaoru <kaoru-esashika@cybozu.co.jp>

Documentation/CRDs/Cluster/ceph-cluster-crd.md

@@ -220,8 +220,9 @@ Configure the network that will be enabled for the cluster and services.
       See the kernel requirements above for encryption.
 
 !!! caution
-    Changing networking configuration after a Ceph cluster has been deployed is NOT
-    supported and will result in a non-functioning cluster.
+    Changing networking configuration after a Ceph cluster has been deployed is only supported for
+    the network encryption settings. Changing other network settings is *NOT* supported and will
+    likely result in a non-functioning cluster.
 
 #### Provider