title: Mutating a Kubernetes deployment yaml for tolerations doc is missing
body: <p>I created a mutating admission webhook in my Kubernetes cluster.
  The api mutation webhook adds tolerations to a Deployment YAML.
  However, it says an error <code>Internal error occurred: jsonpatch add operation does not apply: doc is missing path: "/spec/template/spec/tolerations/"</code></p>
  
  <p>My Yaml Sample file:</p>
  
  <pre><code>apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: nginx
    namespace: webhook
    labels:
      app: nginx 
  spec:
    replicas: 1
    selector:
      matchLabels:
        app: nginx
    strategy:
      rollingUpdate:
        maxSurge: 100%
        maxUnavailable: 50%
      type: RollingUpdate
    template:
      metadata:
        labels:
          app: nginx
      spec:
        containers:
          - name: nginx
            image: "nginx:1.17"
            imagePullPolicy: Always
            ports:
              - containerPort: 80
                name: nginx
  </code></pre>
  
  <p>Python code:</p>
  
  <pre><code>     mutations = []
       mutations.append({"op": "add", "path": "/spec/template/spec/tolerations/" + str(counter),
   "value": {key: t[key]}})
  </code></pre>
  
  <p>However, upon testing error appears as stated above.
  Please help. :(</p>