feat!: Improve Pull Request Template & Contributing Guidelines (#750)

* feat: improve documentation and require changelog

Signed-off-by: Oliver Bähler <oliverbaehler@hotmail.com>

* Bump Versions

Signed-off-by: Oliver Bähler <oliverbaehler@hotmail.com>

* Bump argo-rollouts

Signed-off-by: Marco Kilchhofer <mkilchhofer@users.noreply.github.com>

* Apply suggestions from code review

Signed-off-by: Marco Kilchhofer <mkilchhofer@users.noreply.github.com>

* Reword Artifacthub -> Artifact Hub

Signed-off-by: Marco Kilchhofer <mkilchhofer@users.noreply.github.com>

Co-authored-by: Marco Kilchhofer <mkilchhofer@users.noreply.github.com>

charts/argo-events/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v2
 description: A Helm chart to install Argo-Events in k8s Cluster
 name: argo-events
-version: 1.6.2
+version: 1.6.4
 keywords:
   - argo-events
   - sensor-controller
@@ -15,3 +15,6 @@ maintainers:
 appVersion: 1.3.1
 icon: https://raw.githubusercontent.com/argoproj/argo/master/docs/assets/argo.png
 home: https://github.com/argoproj/argo-helm
+annotations:
+  artifacthub.io/changes: |
+    - "[Added]: Initialize Changelog"