Clarify database health status (#2380)

Copied from the PR #2370

Author: NataliaIvakina

modules/ROOT/pages/monitoring/causal-cluster/http-endpoints.adoc

@@ -139,19 +139,24 @@ Therefore, details such as `leader` and `raftCommandsPerSecond` are database spe
 ====
 
 .Status endpoint descriptions
-[options="header", cols="2,1,1,2,4"]
+[options="header", cols="2,1,1,2,4a"]
 |===
 | Field                          | Type     |Optional| Example                                | Description
 | `core`                         | boolean  | no     | `true`                                 | Used to distinguish between Core Servers and Read Replicas.
 | `lastAppliedRaftIndex`         | number   | no     | `4321`                                 | Every transaction in a cluster is associated with a raft index.
-
-                                                                                              Gives an indication of what the latest applied raft log index is.
+Gives an indication of what the latest applied raft log index is.
 | `participatingInRaftGroup`     | boolean  | no     | `false`                                | A participating member is able to vote.
                                                                                               A Core is considered participating when it is part of the voter membership and has kept track of the leader.
 | `votingMembers`                | string[] | no     | `[]`                                   | A member is considered a voting member when the leader has been receiving communication with it.
+List of member's `memberId` that are considered part of the voting set by this Core.
+| `isHealthy`                      | boolean  | no     | `true`                                 | Indicates that the local database on this cluster member has not encountered a critical error that can block database operation.
 
-                                                                                              List of member's `memberId` that are considered part of the voting set by this Core.
-| `isHealthy`                      | boolean  | no     | `true`                                 | Reflects that the local database of this member has not encountered a critical error preventing it from writing locally.
+[CAUTION]
+====
+The `isHealthy` status applies only to this member's local database.
+It does not reflect the overall health of the database if it is clustered.
+A cluster member may still report `"isHealthy": true` even if the database currently has no leader and so cannot accept write transactions.
+====
 | `memberId`                     | string   | no     | `30edc1c4-519c-4030-8348-7cb7af44f591` | Every member in a cluster has it's own unique member id to identify it.
                                                                                               Use `memberId` to distinguish between Core and Read Replica.
 | `leader`                       | string   | yes    | `80a7fb7b-c966-4ee7-88a9-35db8b4d68fe` | Follows the same format as `memberId`, but if it is null or missing, then the leader is unknown.