docs(readme): update

Author: teppeis

README.md

@@ -17,6 +17,7 @@ $ npm install -D espower-typescript
 
 ## TypeScript versions
 
+* espower-typescript v8.x uses TypeScript v2.2
 * espower-typescript v7.x uses TypeScript v2.1
 * espower-typescript v6.x uses TypeScript v2.0
 * espower-typescript v5.x uses TypeScript v1.8