Add Andreu Botella as a champion (tc39#89)

Author: legendecas

README.md

@@ -4,6 +4,7 @@ Status: Stage 2
 
 Champions:
 
+- Andreu Botella ([@andreubotella](https://github.com/andreubotella))
 - Chengzhong Wu ([@legendecas](https://github.com/legendecas))
 - Justin Ridgewell ([@jridgewell](https://github.com/jridgewell))