Update README.md

Author: jackbrookes

README.md

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 # UXF - Unity Experiment Framework
 A set of components which simplify human behaviour experiments developed in the Unity engine. This is the development project, if you want to download the package, see [Releases](https://github.com/jackbrookes/unity-experiment-framework/releases/latest). 
 
+If you have developed a project using UXF please [let me know](http://twitter.com/jackbrookes)! 
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 ## Get started
 
 1. Import the latest ```UXF.unitypackage``` [release](https://github.com/jackbrookes/unity-experiment-framework/releases/latest) to your existing Unity project.