[ADF-3682] Review of main README and other information pages (#3892)

* [ADF-3682] Updated text, links and info in README files

* [ADF-3682] Reviewed text of CORS info page

* [ADF-3682] Fixed minor typo in README.md

PREREQUISITES.md

@@ -1,27 +1,11 @@
 # Prerequisites for building and running apps with the Alfresco Application Development Framework
 
-The [Angular](https://angular.io/) based application development framework requires the following:
+See our tutorial
+[Preparing the development environment](docs/tutorials/preparing-environment.md)
+for full details of what you need to install before using ADF.
 
-- An Alfresco Platform Repository (version [201609 Early Access](https://community.alfresco.com/docs/DOC-6372-alfresco-community-edition-file-list-201609-ea) or newer) 
-- [Download and install the process service](https://www.alfresco.com/products/bpm/alfresco-activiti/trial)
-- [Node.js](https://nodejs.org/en/) JavaScript runtime.
-- [npm](https://www.npmjs.com/) package manager for JavaScript.
-- (If you use CS and PS together) Make sure your user has the same username and password in both system
-- [If you are experiencing CORS problem read this guide](/ALFRESCOCORS.md)
-
-*Note: Default username for activiti is "admin@app.activiti.com" and "admin" for Alfresco, and also the default password are different. Change them to be equal.*
-
-**Verify that you are running at least node `v5.x.x` and npm `3.x.x`**
-by running `node -v` and `npm -v` in a terminal/console window.
-Older versions produce errors.
-
-## Installing Node.js
-
-If you don't have Node.js installed then access this [page](https://nodejs.org/en/download/) and use the appropriate installer for your OS.
-
-Make sure the Node.js version is > 5:
-
-```
-$ node -v
-v5.12.0
-```
+If you experience [CORS](https://en.wikipedia.org/wiki/Cross-origin_resource_sharing)
+issues then you should also read our
+[CORS guide](ALFRESCOCORS.md)
+to see the full range of solutions available.
+