Update 'Who uses RichTextFX?' (#825)

Add Chorus to 'Who uses RichTextFX?' section

Author: iamgio

README.md

@@ -57,7 +57,8 @@ Who uses RichTextFX?
 - [JDialogue](https://github.com/SkyAphid/JDialogue)
 - [George](http://www.george.andante.no)
 - [Nearde IDE](https://github.com/VenityStudio/Nearde-IDE)
-- [Astro IDE](https://github.com/AmrDeveloper/Astro)
+- [Astro IDE](https://github.com/AmrDeveloper/Astro) 
+- [Chorus](https://github.com/iAmGio/chorus)
 
 If you use RichTextFX in an interesting project, I would like to know!