[DOCS] Fix gcloud command typo in discovery-gce.asciidoc. (#47312)

Author: mattayes

docs/plugins/discovery-gce.asciidoc

@@ -327,7 +327,7 @@ 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
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