add some notes to the README about syncing changes from original manifests/install.yaml

Signed-off-by: Marcel Hoyer <mhoyer@pixelplastic.de>

charts/argo-cd/README.md

@@ -12,6 +12,26 @@ The default installation is intended to be similar to the provided ArgoCD [relea
 
 This chart currently installs the non-HA version of ArgoCD.
 
+### Synchronizing Changes from Original Repository
+
+In the original [ArgoCD repository](https://github.com/argoproj/argo-cd/) an [`manifests/install.yaml`](https://github.com/argoproj/argo-cd/blob/master/manifests/install.yaml) is generated using `kustomize`. It's the basis for the installation as [described in the docs](https://argo-cd.readthedocs.io/en/stable/getting_started/#1-install-argo-cd).
+
+When installing ArgoCD using this helm chart the user should have a similar experience and configuration rolled out. Hence, it makes sense to try to achieve a similar output of rendered `.yaml` resources when calling `helm template` using the default settings in `values.yaml`.
+
+To update the templates and default settings in `values.yaml` it may come in handy to look up the diff of the `manifests/install.yaml` between two versions accordingly. This can either be done directly via github and look for `manifests/install.yaml`:
+
+https://github.com/argoproj/argo-cd/compare/v1.8.7...v2.0.0#files_bucket
+
+Or you clone the repository and do a local `git-diff`:
+
+```bash
+git clone https://github.com/argoproj/argo-cd.git
+cd argo-cd
+git diff v1.8.7 v2.0.0 -- manifests/install.yaml
+```
+
+Changes in the `CustomResourceDefinition` resources shall be fixed easily by copying 1:1 from the [`manifests/crds` folder](https://github.com/argoproj/argo-cd/tree/master/manifests/crds) into this [`charts/argo-cd/crds` folder](https://github.com/argoproj/argo-helm/tree/master/charts/argo-cd/crds).
+
 ## Upgrading
 
 ### 3.0.0 and above