update instructions for skaffold

README.md

@@ -28,7 +28,7 @@ PREREQUISITES: Cloud Build service account must have role: "Kubernetes Engine De
 
 ```bash
 export GOOGLE_APPLICATION_CREDENTIALS=my-service-account.json
-skaffold run -p gcb --default-repo=gcr.io/[PROJECT_ID]
+skaffold run -p gcb --default-repo=gcr.io/$PROJECT_ID
 ```
 
 * Option 2 - local docker
@@ -39,6 +39,14 @@ skaffold run --default-repo=gcr.io/[PROJECT_ID]
 
 NOTE: `client` and `load-test` are not installed.
 
+#### Installing a single application
+
+```bash
+skaffold run -p gcb --default-repo=gcr.io/$PROJECT_ID -f skaffold-{appname}.yaml
+```
+
+where {appname} can be orders, inventory, tracking, customers or websockets
+
 ### Skaffold Errors
 
 When rerunning/installing the applications, you may observe errors like this: