Update db-availability.md (#1637)

* Update db-availability.md

clearer status code description

* Update content/operate/rs/monitoring/db-availability.md

---------

Co-authored-by: Rachel Elledge <86307637+rrelledge@users.noreply.github.com>

Author: maayanagranat

content/operate/rs/monitoring/db-availability.md

@@ -41,7 +41,7 @@ To check database availability when using a load balancer and the recommended `a
 GET /v1/local/bdbs/<database_id>/endpoint/availability
 ```
 
-Returns the status code 200 OK if the local database endpoint is available.
+Returns HTTP status code 200 OK if all primary (master) shards are reachable from the local database endpoint.
 
 If the local database endpoint is unavailable, returns an error status code and a JSON object that contains [`error_code` and `description` fields]({{<relref "/operate/rs/references/rest-api/requests/bdbs/availability#get-endpoint-error-codes">}}).