Create README.md

README.md

@@ -379,6 +379,8 @@ All of JSX and Flow syntax is supported. In fact, the test suite in
 
 Prettier also supports [TypeScript](https://www.typescriptlang.org/), CSS, [LESS](http://lesscss.org/), and [SCSS](http://sass-lang.com).
 
+The minimum version of TypeScript supported is 2.1.3 as it introduces the ability to have leading `|` for type definitions which prettier outputs.
+
 ## Related Projects
 
 - [`eslint-plugin-prettier`](https://github.com/prettier/eslint-plugin-prettier) plugs Prettier into your ESLint workflow