Add updateStrategy with RollingUpdate as default

Rolling are the default for deployments and parameters should be configurable for the user.

webserver/templates/deployment.yaml

@@ -11,6 +11,9 @@ spec:
   selector:
     matchLabels:
       {{- include "webserver.selectorLabels" . | nindent 6 }}
+  {{- if .Values.webserver.updateStrategy }}
+  strategy: {{- toYaml .Values.webserver.updateStrategy | nindent 4 }}
+  {{- end }}
   template:
     metadata:
       {{- with .Values.podAnnotations }}