Add docs about working with argocd

Signed-off-by: RainbowMango <qdurenhongcai@gmail.com>

docs/working-with-argocd.md

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+# Working with Argo CD
+
+This topic walks you through how to use the [Argo CD](https://github.com/argoproj/argo-cd/) to manage your workload 
+`across clusters` with `Karmada`.
+
+## Prerequisites
+### Argo CD Installation
+You have installed Argo CD following the instructions in [Getting Started](https://argo-cd.readthedocs.io/en/stable/getting_started/#getting-started).
+
+### Karmada Installation
+In this example, we are using a Karmada environment with at lease `3` member clusters joined.
+
+You can set up the environment by `hack/karmada-bootstrap.sh`, which is also used to run our E2E cases.
+
+```bash
+# kubectl get clusters
+NAME      VERSION   MODE   READY   AGE
+member1   v1.19.1   Push   True    18h
+member2   v1.19.1   Push   True    18h
+member3   v1.19.1   Pull   True    17h
+```
+
+## Registering Karmada to Argo CD
+This step registers Karmada control plane to Argo CD.
+
+First list the contexts of all clusters in your current kubeconfig:
+```bash
+kubectl config get-contexts -o name
+```
+
+Choose the context of the Karmada control plane from the list and add it to `argocd cluster add CONTEXTNAME`. 
+For example, for `karmada-apiserver` context, run:
+```bash
+argocd cluster add karmada-apiserver
+```
+
+If everything goes well, you can see the registered Karmada control plane from the Argo CD UI, e.g.:
+
+![](./images/argocd-register-karmada.png)
+
+## Creating Apps Via UI
+
+### Preparing Apps
+Take the [guestbook](https://github.com/argoproj/argocd-example-apps/tree/53e28ff20cc530b9ada2173fbbd64d48338583ba/guestbook) 
+as example.
+
+First, fork the [argocd-example-apps](https://github.com/argoproj/argocd-example-apps) repo and create a branch 
+`karmada-demo`.
+
+Then, create a [PropagationPolicy manifest](https://github.com/RainbowMango/argocd-example-apps/blob/e499ea5c6f31b665366bfbe5161737dc8723fb3b/guestbook/propagationpolicy.yaml) under the `guestbook` directory.
+
+### Creating Apps
+
+Click the `+ New App` button as shown below:
+
+![](./images/argocd-new-app.png)
+
+Give your app the name `guestbook-multi-cluster`, use the project `default`, and leave the sync policy as `Manual`:
+
+![](./images/argocd-new-app-name.png)
+
+Connect the `forked repo` to Argo CD by setting repository url to the github repo url, set revision as `karmada-demo`, 
+and set the path to `guestbook`:
+
+![](./images/argocd-new-app-repo.png)
+
+For Destination, set cluster to `karmada` and namespace to `default`:
+
+![](./images/argocd-new-app-cluster.png)
+
+### Syncing Apps
+You can sync your applications via UI by simply clicking the SYNC button and following the pop-up instructions, e.g.:
+
+![](./images/argocd-sync-apps.png)
+
+More details please refer to [argocd guide: sync the application](https://argo-cd.readthedocs.io/en/stable/getting_started/#7-sync-deploy-the-application).
+
+## Checking Apps Status
+For deployment running in more than one clusters, you don't need to create applications for each 
+cluster. You can get the overall and detailed status from one `Application`.
+
+![](./images/argocd-status-overview.png)
+
+The `svc/guestbook-ui`, `deploy/guestbook-ui` and `propagationpolicy/guestbook` in the middle of the picture are the 
+resources created by the manifest in the forked repo. And the `resourcebinding/guestbook-ui-service` and 
+`resourcebinding/guestbook-ui-deployment` in the right of the picture are the resources created by Karmada.
+
+### Checking Detailed Status
+You can obtain the Deployment's detailed status by `resourcebinding/guestbook-ui-deployment`. 
+
+![](./images/argocd-status-resourcebinding.png)
+
+### Checking Aggregated Status
+You can obtain the aggregated status of the Deployment from UI by `deploy/guestbook-ui`.
+
+![](./images/argocd-status-aggregated.png)