chore: Fix some grammatical errors in cluster alerts

Signed-off-by: Vincent Liu <[email protected]>

Author: Vincent-lau

ocaml/xapi/xapi_cluster_helpers.ml

@@ -157,7 +157,7 @@ let maybe_generate_alert ~__context ~num_hosts ~hosts_left ~hosts_joined ~quorum
       let name, priority = Api_messages.cluster_quorum_approaching_lost in
       let body =
         Printf.sprintf
-          "The cluster is losing quorum: current %d hosts, need %d hosts for a \
+          "The cluster is losing quorum: currently %d host(s), need %d hosts for a \
            quorum"
           num_hosts quorum
       in