/docs/samples revamp: move examples to /tutorials

Addresses the work described at #4134.

- Remove /docs/samples page: This page mostly had links to examples on
  kubernetes/kubernetes (examples dir) which is now at kubernetes/examples
  repository. It was linking to README.md files for tutorials. Now removing
  this page as we are moving tutorials from kubernetes/examples to here:

  - Create redirects from /docs/samples/ to /docs/tutorials/ (both JS and
    redirect_from).
  - Deprecate "MEAN Stack" tutorial: This tutorial overlaps quite a bit with
    existing "maintained" examples and has been out-of-date for a while.
    Creating an external redirect to its original and more up-to-date location:
    https://medium.com/google-cloud/running-a-mean-stack-on-google-cloud-platform-with-app-engine-and-mongolab-4bbd2040ea75

- Import README.md files of maintained examples (guestbook, wordpress+mysql and
  cassandra) to this repository and serve them under /docs/tutorial.

- Update /docs/tutorials ToC:
  - Link to imported tutorials.
  - Fix missing articles on sidebar (_data/tutorials.yml) and make the tutorials
    listed on tutorials/index.md available on the sidebar (closes #4007).

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

_data/samples.yml

@@ -1,75 +0,0 @@
-bigheader: "Samples"
-abstract: "A collection of example applications that show how to use Kubernetes."
-toc:
-- docs/samples.md
-
-- title: Storage / Database / KV
-  section:
-  - title: Apache Cassandra Database
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/storage/cassandra
-  - title: Ceph
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/volumes/rbd/
-  - title: CephFS
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/volumes/cephfs/
-  - title: CockroachDB
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/cockroachdb/
-  - title: GlusterFS
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/volumes/glusterfs/
-  - title: Hazelcast
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/storage/hazelcast
-  - title: iSCSI
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/volumes/iscsi/
-  - title: MySQL Galera
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/storage/mysql-galera
-  - title: NFS
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/volumes/nfs/
-  - title: Redis
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/storage/redis/
-  - title: RethinkDB
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/storage/rethinkdb/
-  - title: Vitess
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/storage/vitess/
-
-- title: Big Data
-  section:
-  - title: Apache Spark
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/spark
-  - title: Apache Storm
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/storm
-
-- title: Messaging / Queueing
-  section:
-  - title: Hazelcast
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/storage/hazelcast
-
-- title: Miscellaneous
-  section:
-  - title: Meteor Applications
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/meteor/
-  - title: OpenShift Origin
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/openshift-origin/
-  - title: Selenium
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/selenium/
-
-- title: Monitoring and Logging
-  section:
-  - title: Elasticsearch
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/elasticsearch/
-  - title: NewRelic
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/newrelic
-
-- title: Multi-tier Applications
-  section:
-  - title: Guestbook - Go Server
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/guestbook-go/
-  - title: GuestBook - PHP Server
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/guestbook/
-  - docs/getting-started-guides/meanstack.md
-  - title: MySQL + Wordpress
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/mysql-wordpress-pd/
-  - title: MySQL + Phabricator Server
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/phabricator/
-  - title: Nodejs + Mongo
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/nodesjs-mongodb
-  - title: Petstore
-    path: https://github.com/kubernetes/kubernetes/tree/release-1.6/examples/k8petstore/

_data/tutorials.yml

@@ -43,10 +43,17 @@ toc:
   - docs/tutorials/object-management-kubectl/declarative-object-management-configuration.md
 - title: Stateless Applications
   section:
+  - docs/tasks/run-application/run-stateless-application-deployment.md
+  - docs/tutorials/stateless-application/guestbook.md
+  - docs/tasks/access-application-cluster/service-access-application-cluster.md
   - docs/tutorials/stateless-application/expose-external-ip-address.md
 - title: Stateful Applications
   section:
   - docs/tutorials/stateful-application/basic-stateful-set.md
+  - docs/tasks/run-application/run-single-instance-stateful-application.md
+  - docs/tasks/run-application/run-replicated-stateful-application.md
+  - docs/tutorials/stateful-application/mysql-wordpress-persistent-volume.md
+  - docs/tutorials/stateful-application/cassandra.md
   - docs/tutorials/stateful-application/zookeeper.md
 - title: Clusters
   section: