Service Catalog docs (#5867)

* Service Catalog docs (+16 squashed commits)
Squashed commits:
[765e81d] rework install-service-catalog.md
[d81f799] tweak diagrams
[b7a3da7] Add tooltips
[3b256c5] more rework
[828000e] architecture diagram redux
[0b809d5] rework
[7829301] Outline provision-bind-external-service.md w/ filler text
[144fbb3] install service catalog v1
[47b5be4] Reorder images and bullet points
[fb577ae] Update What's Next links
[8ac984c] Include snippet for install and provision docs
[c2eeece] Add Install Service Catalog doc
[a84df64] Add hard line break
[7fb12c6] Add task
[75c46d3] Add List, Provision, and Bind diagrams
[6386feb] Service Catalog concept doc

* Add install-service-catalog-using-helm

* switch mysql examples to message queuing instead

* Incorporate feedback

* incorporate additional feedback

* Incorporate tech review feedback

_data/tasks.yml

@@ -100,7 +100,7 @@ toc:
   - title: Use Explorer to Examine the Runtime Environment
     path: https://github.com/kubernetes/kubernetes/tree/release-1.5/examples/explorer
 
-- title: Access and Extend the Kubernetes API
+- title: Extend Kubernetes
   section:
   - docs/tasks/access-kubernetes-api/http-proxy-access-api.md
   - docs/tasks/access-kubernetes-api/extend-api-custom-resource-definitions.md
@@ -108,6 +108,8 @@ toc:
   - docs/tasks/access-kubernetes-api/migrate-third-party-resource.md
   - docs/tasks/access-kubernetes-api/configure-aggregation-layer.md
   - docs/tasks/access-kubernetes-api/setup-extension-api-server.md
+  - docs/tasks/service-catalog/install-service-catalog-using-helm.md
+  - docs/tasks/service-catalog/install-service-catalog-using-sc.md
 
 - title: TLS
   section: