Add additional help guidance on HMRClient close event

Summary:
Resolves [comment on #35514](#35514 (comment)).

Changelog: [Internal]

Reviewed By: arushikesarwani94

Differential Revision: D42166587

fbshipit-source-id: bb9a28874727e7df45a73d86a876b3d6febe70da

Author: huntie

Libraries/Utilities/HMRClient.js

@@ -252,13 +252,18 @@ Error: ${e.message}`;
         closeEvent.code === 1005 ||
         closeEvent.code == null;
 
-      if (isNormalOrUnsetCloseReason) {
-        setHMRUnavailableReason('Disconnected from Metro.');
-      } else {
-        setHMRUnavailableReason(
-          `Disconnected from Metro (${closeEvent.code}: "${closeEvent.reason}").`,
-        );
-      }
+      setHMRUnavailableReason(
+        `${
+          isNormalOrUnsetCloseReason
+            ? 'Disconnected from Metro.'
+            : `Disconnected from Metro (${closeEvent.code}: "${closeEvent.reason}").`
+        }
+
+To reconnect:
+- Ensure that Metro is running and available on the same network
+- Reload this app (will trigger further help if Metro cannot be connected to)
+      `,
+      );
     });
 
     if (isEnabled) {