fix metrics image and merge resource folders

Signed-off-by: Hongchao Deng <hongchaodeng1@gmail.com>

README.md

@@ -1,4 +1,4 @@
-![alt](resources/KubeVela-03.png)
+![alt](docs/resources/KubeVela-03.png)
 
 *Make shipping applications more enjoyable.*
 

docs/_sidebar.md

@@ -9,7 +9,7 @@
     - [Setting Routes](/en/developers/set-route.md)
     - [Setting Auto-scaling Policy](/en/developers/set-autoscale.md)
     - [Setting Rollout Strategy](/en/developers/set-rollout.md)
-    - [Monitoring Application](/en/developers/set-metrics.md)
+    - [Setting Monitoring Policy](/en/developers/set-metrics.md)
   - Debugging
     - [Check Application Logs](/en/developers/check-logs.md)
     - [Execute Commands in Container](/en/developers/exec-cmd.md)  

docs/en/developers/set-metrics.md

@@ -68,4 +68,4 @@ kubectl --namespace monitoring port-forward `kubectl -n monitoring get pods -l p
 
 Then access the prometheus dashboard via http://localhost:9090/targets
 
-![Prometheus Dashboard](../../../resources/metrics.jpg)
+![Image of Prometheus Dashboard](../../resources/metrics.jpg)