Add warnings for top-down approach pages (#626)

* add warnings for top-down approach pages

* Update READMEs from other repos
APPROVED

pages/en/lb3/readmes/loopback-component-push.md

@@ -31,7 +31,7 @@ providers such as APNS, GCM, and MPNS
 
 ### Node.js server
 
-This module includes an [example LoopBack server application](https://github.com/strongloop/loopback-component-push/tree/master/example/server-2.0).  
+This module includes an [example LoopBack server application](https://github.com/strongloop/loopback-example-push).  
 
 To run it, use these commands:
 
@@ -53,12 +53,12 @@ MONGODB=mongodb://localhost/demo node app
 
 ### iOS client
 
-The [iOS example app](https://github.com/strongloop/loopback-component-push/tree/master/example/ios)
+The [iOS example app](https://github.com/strongloop/loopback-example-push/tree/master/ios)
 uses the LoopBack iOS SDK to enable and handle push notifications. 
 
 ### Android client
 
-The [Android example app](https://github.com/strongloop/loopback-component-push/tree/master/example/android)
+The [Android example app](https://github.com/strongloop/loopback-example-push/tree/master/android)
 uses the LoopBack Android SDK to enable and handle push notifications. 
 
 ## References

pages/en/lb4/Defining-and-validating-the-API.md

@@ -7,6 +7,10 @@ sidebar: lb4_sidebar
 permalink: /doc/en/lb4/Defining-and-validating-the-API.html
 summary:
 ---
+{% include important.html content="The top-down approach for building LoopBack
+applications is not yet fully supported. Therefore, the steps outlined in this
+page are outdated and may not work out of the box. They will be revisited after
+our MVP release." %}
 
 ## Define the API
 

pages/en/lb4/Testing-the-API.md

@@ -12,6 +12,11 @@ summary:
 This article continues off from [Defining and validating the API](./Defining-and-validating-the-API.html).
 " %}
 
+{% include important.html content="The top-down approach for building LoopBack
+applications is not yet fully supported. Therefore, the steps outlined in this
+page are outdated and may not work out of the box. They will be revisited after
+our MVP release." %}
+
 ## Smoke test API input/output
 
 Once you confirm that the API specification is valid, it's time to verify that the application implements the API as you have specified it.  The input/output testing described below uses [Dredd](https://www.npmjs.com/package/dredd), specifically `hello-world` in this section.  Concrete sample code of `hello-world` can be found in the [hello-world tutorial](https://github.com/strongloop/loopback-next-hello-world) repository.  Although the sample code includes a validated API spec and fully functional `hello-world` controller, let's pretend the controller is completely empty.  Try it yourself by cloning the repository from GitHub.