[WIP] Attempt to consolidate YAML files (#8965)

This is an attempt to consolidate YAML files so that:

- They can remain untouched when we moving the documents around;
- Contributors do not have to change the test cases each time a
  documentation is moved;
- We can encourage referencing the existing YAMLs from different
  concept or task pages when possible.

content/en/docs/tasks/run-application/deployment.yaml

@@ -1,21 +0,0 @@
-apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
-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

content/en/docs/tasks/run-application/run-stateless-application-deployment.md

@@ -36,12 +36,12 @@ You can run an application by creating a Kubernetes Deployment object, and you
 can describe a Deployment in a YAML file. For example, this YAML file describes
 a Deployment that runs the nginx:1.7.9 Docker image:
 
-{{< code file="deployment.yaml" >}}
+{{< codenew file="application/deployment.yaml" >}}
 
 
 1. Create a Deployment based on the YAML file:
 
-        kubectl apply -f https://k8s.io/docs/tasks/run-application/deployment.yaml
+        kubectl apply -f https://k8s.io/docs/artifacts/application/deployment.yaml
 
 1. Display information about the Deployment: