Consolidate YAML files [part-2] (#9236)

Changes that will help upcoming consolidation work:

- Add variable `githubWebsiteRaw` to config.toml to facilitate building
  links to raw YAML files
- Revise `codenew` shortcode to generate links to raw YAML files instead
  of github.com file view;
- Rename `artifacts` directory to `examples` to better reflect its usage;

Accompanied changes as show cases:

- Moved `deployment.yaml`, `deployment-update.yaml` and
  `deployment-scale.yaml` to the new `examples/application` subdirectory;
- Removed duplicate instances of the above YAML files in other
  directories;
- Update example_test.go to test the relocated YAML files and removed
  testing for files that no longer needed.

content/en/docs/tutorials/stateless-application/deployment.yaml

@@ -1,21 +0,0 @@
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  name: nginx-deployment
-spec:
-  selector:
-    matchLabels:
-      app: nginx
-  replicas: 2 # tells deployment to run 2 pods matching the template
-  template: # create pods using pod definition in this template
-    metadata:
-      # unlike pod-nginx.yaml, the name is not included in the meta data as a unique name is
-      # generated from the deployment name
-      labels:
-        app: nginx
-    spec:
-      containers:
-      - name: nginx
-        image: nginx:1.7.9
-        ports:
-        - containerPort: 80