ci: Update FOTA state machine plantUML

Update the FOTA state machine to accurately reflect how
FOTA_DOWNLOAD_CANCEL is handled.

Signed-off-by: Jan Tore Guggedal <jantore.guggedal@nordicsemi.no>

Author: jtguggedal

tests/state_machines/source_of_truth/fota.puml

@@ -6,8 +6,13 @@ state STATE_RUNNING
 STATE_RUNNING --> STATE_CANCELING: FOTA_DOWNLOAD_CANCEL
 
 state STATE_RUNNING {
-    state STATE_WAITING_FOR_POLL_REQUEST
-    state STATE_POLLING_FOR_UPDATE
+    state STATE_WAITING_FOR_POLL_REQUEST {
+        STATE_WAITING_FOR_POLL_REQUEST : FOTA_DOWNLOAD_CANCEL /
+    }
+    state STATE_POLLING_FOR_UPDATE {
+        STATE_POLLING_FOR_UPDATE : entry / nrf_cloud_fota_poll_process()
+        STATE_POLLING_FOR_UPDATE : FOTA_DOWNLOAD_CANCEL /
+    }
     state STATE_DOWNLOADING_UPDATE
     state STATE_WAITING_FOR_IMAGE_APPLY
     state STATE_IMAGE_APPLYING