Removed non-md files from docs. Moved doc yamls to test/fixtures.

Most of the contents of docs/ has moved to kubernetes.github.io.
Development of the docs and accompanying files has continued there, making
the copies in this repo stale. I've removed everything but the .md files
which remain to redirect old links. The .yaml config files in the docs
were used by some tests, these have been moved to test/fixtures/doc-yaml,
and can remain there to be used by tests or other purposes.

docs/user-guide/downward-api/dapi-pod.yaml

@@ -1,23 +0,0 @@
-apiVersion: v1
-kind: Pod
-metadata:
-  name: dapi-test-pod
-spec:
-  containers:
-    - name: test-container
-      image: gcr.io/google_containers/busybox
-      command: [ "/bin/sh", "-c", "env" ]
-      env:
-        - name: MY_POD_NAME
-          valueFrom:
-            fieldRef:
-              fieldPath: metadata.name
-        - name: MY_POD_NAMESPACE
-          valueFrom:
-            fieldRef:
-              fieldPath: metadata.namespace
-        - name: MY_POD_IP
-          valueFrom:
-            fieldRef:
-              fieldPath: status.podIP
-  restartPolicy: Never

docs/user-guide/downward-api/volume/dapi-volume.yaml

@@ -1,30 +0,0 @@
-apiVersion: v1
-kind: Pod
-metadata:
-  name: kubernetes-downwardapi-volume-example
-  labels:
-    zone: us-est-coast
-    cluster: test-cluster1
-    rack: rack-22
-  annotations:
-    build: two
-    builder: john-doe
-spec:
-  containers:
-    - name: client-container
-      image: gcr.io/google_containers/busybox
-      command: ["sh", "-c", "while true; do if [[ -e /etc/labels ]]; then cat /etc/labels; fi; if [[ -e /etc/annotations ]]; then cat /etc/annotations; fi; sleep 5; done"]
-      volumeMounts:
-        - name: podinfo
-          mountPath: /etc
-          readOnly: false
-  volumes:
-    - name: podinfo
-      downwardAPI:
-        items:
-          - path: "labels"
-            fieldRef:
-              fieldPath: metadata.labels
-          - path: "annotations"
-            fieldRef:
-              fieldPath: metadata.annotations