Updates GCP experiment charts (#548)

* removed .DS_Store

Signed-off-by: Neelanjan Manna <neelanjan.manna@harness.io>

* corrected gcp-vm-instance-stop-by-label charts

Signed-off-by: Neelanjan Manna <neelanjan.manna@harness.io>

* updated experiment charts

Signed-off-by: Neelanjan Manna <neelanjan.manna@harness.io>

* updated experiment descriptions

Signed-off-by: Neelanjan Manna <neelanjan.manna@harness.io>

* updated instance-stop-by-label charts for INSTANCE_AFFECTED_PERC env

Signed-off-by: Neelanjan Manna <neelanjan.manna@harness.io>

charts/gcp/gcp-vm-instance-stop-by-label/experiment.yaml

@@ -1,7 +1,7 @@
 apiVersion: litmuschaos.io/v1alpha1
 description:
   message: |
-    gcp-vm-instance stop by label experiment causes gcp vm instances specified by a label to be stopped for a given time duration
+    Stops GCP VM instances and GKE nodes filtered by a label for a specified duration and later restarts them 
 kind: ChaosExperiment
 metadata:
   name: gcp-vm-instance-stop-by-label
@@ -78,6 +78,11 @@ spec:
     # enable it if the target instance is a part of a managed instance group
     - name: MANAGED_INSTANCE_GROUP
       value: 'disable'
+
+    # set the percentage value of the instances with the given label 
+    # which should be targeted as part of the chaos injection
+    - name: INSTANCE_AFFECTED_PERC
+      value: ''
       
     labels:
       name: gcp-vm-instance-stop-by-label