Update amber website URL (#3113)

This PR updates Amber Framework website URL on README

https://www.ambercr.io to https://amberframework.org

frameworks/Crystal/amber/README.md

@@ -1,8 +1,8 @@
 # Welcome to Amber
 
-This is the [Amber](https://www.ambercr.io) test of the Framework Benchmarks.
+This is the [Amber](https://amberframework.org) test of the Framework Benchmarks.
 
-[![Amber logo](https://i.imgur.com/NEodgHV.png)](https://www.ambercr.io)
+[![Amber logo](https://i.imgur.com/NEodgHV.png)](https://amberframework.org)
 
 **Amber** is a web application framework written in [Crystal](http://www.crystal-lang.org) inspired by Kemal, Rails, Phoenix and other popular application frameworks.
 
@@ -21,4 +21,4 @@ Amber Crystal borrows concepts that already have been battle tested, successful,
 
 ## License
 
-This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.