helm: specify icon

Use the favicon image that was lately added to the documentation.

Also, update the prepare-release script to take the icon from the
release.

Author: marquiz

deployment/helm/node-feature-discovery/Chart.yaml

@@ -1,5 +1,6 @@
 apiVersion: v2
 appVersion: master
+icon: https://kubernetes-sigs.github.io/node-feature-discovery/master/assets/images/nfd/favicon.svg
 description: |
   Detects hardware features available on each node in a Kubernetes cluster, and advertises
   those features using node labels.

hack/prepare-release.sh

@@ -131,7 +131,9 @@ if [ -z "$no_patching" ]; then
 
     # Patch Helm chart
     echo "Patching Helm chart"
-    sed -e s"/appVersion:.*/appVersion: $release/" -i deployment/helm/node-feature-discovery/Chart.yaml
+    sed -e s"/appVersion:.*/appVersion: $release/" \
+        -e s"!icon:.*!icon: https://kubernetes-sigs.github.io/node-feature-discovery/$docs_version/assets/images/nfd/favicon.svg!" \
+        -i deployment/helm/node-feature-discovery/Chart.yaml
     sed -e s"/pullPolicy:.*/pullPolicy: IfNotPresent/" \
         -e s"!gcr.io/k8s-staging-nfd/node-feature-discovery!registry.k8s.io/nfd/node-feature-discovery!" \
         -i deployment/helm/node-feature-discovery/values.yaml