update README to RC4. could have done that pre-release :-(

Author: Nikolaus Kühn

README.md

@@ -1,7 +1,8 @@
 ![SPHERE.IO icon](https://admin.sphere.io/assets/images/sphere_logo_rgb_long.png)
 # SPHERE.IO PHP SDK
 
-> STATUS: technically robust beta version, but we do not yet guarantee API compatibility until the 1.0.0 release.  Please take your time to thoroughly test the upcoming RC (Milestone 4) release.
+> STATUS: Release Candidate 1.  We have done all planned breaking changes and ask you to really use this API thoroughly now, especially the API design and object structure. Thank you very much!  
+> 
 > See the [Milestone Plan](https://github.com/sphereio/sphere-php-sdk/milestones?direction=desc&sort=completeness&state=open) for details of what's planned in detail. We love feedback and [Issue reports](https://github.com/sphereio/sphere-php-sdk/issues?q=is%3Aopen+is%3Aissue+sort%3Acreated-asc)!
 
 [![Build Status](https://img.shields.io/travis/sphereio/sphere-php-sdk/master.svg?style=flat-square)](https://travis-ci.org/sphereio/sphere-php-sdk) [![Scrutinizer](https://img.shields.io/scrutinizer/g/sphereio/sphere-php-sdk.svg?style=flat-square)](https://scrutinizer-ci.com/g/sphereio/sphere-php-sdk/) [![Scrutinizer](https://img.shields.io/scrutinizer/coverage/g/sphereio/sphere-php-sdk.svg?style=flat-square)](https://scrutinizer-ci.com/g/sphereio/sphere-php-sdk/) [![Packagist](https://img.shields.io/packagist/v/sphere/php-sdk.svg?style=flat-square)](https://packagist.org/packages/sphere/php-sdk) [![Packagist](https://img.shields.io/packagist/dm/sphere/php-sdk.svg?style=flat-square)](https://packagist.org/packages/sphere/php-sdk)
@@ -14,7 +15,7 @@ The SDK is licensed under the permissive [MIT License](LICENSE). Don't hesitate
 
 ## Using the SDK
 
-The [PHP API documentation](http://sphereio.github.io/sphere-php-sdk/docs/master) provides all the details you need in a searchable form.
+The [PHP API documentation](http://sphereio.github.io/sphere-php-sdk/docs/master) provides all the details you need in a searchable form (link points to latest stable release).
 
 ### Install & Integrate the SDK into your Project