[DOCS] Fix gcloud command typo in discovery-gce.asciidoc.
@@ -326,7 +326,7 @@ gcloud compute instances delete myesnode1 myesnode2 \
--zone=europe-west1-a
# Consider removing disk as well if you don't need them anymore
-gcloud compute disks deleted boot-myesnode1 boot-myesnode2 \
+gcloud compute disks delete boot-myesnode1 boot-myesnode2 \
--zone=europe-west1-a
--------------------------------------------------
