Simplify TypeScript setup instructions

Author: Timer

docusaurus/docs/adding-typescript.md

@@ -3,18 +3,22 @@ id: adding-typescript
 title: Adding TypeScript
 ---
 
-TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.
+[TypeScript](https://www.typescriptlang.org/) is a typed superset of JavaScript that compiles to plain JavaScript.
 
-Recent versions of [TypeScript](https://www.typescriptlang.org/) work with Create React App projects out of the box thanks to Babel 7. Note that Babel 7 TypeScript does not allow some features of TypeScript such as constant enum and namespaces.
+To add [TypeScript](https://www.typescriptlang.org/) to a Create React App project, first install it:
 
-To add TypeScript to a Create React App project, follow these steps:
+```bash
+$ npm install --save typescript @types/react @types/react-dom @types/jest
+$ # or
+$ yarn add typescript @types/react @types/react-dom @types/jest
+```
 
-1. Run `npm install --save typescript @types/react @types/react-dom @types/jest` (or `yarn add typescript @types/react @types/react-dom @types/jest`).
-2. Rename `src/index.js` to `src/index.tsx` or create an empty [`tsconfig.json` file](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html) at the root project directory.
-3. Restart your development server (if applicable). This will set sensible defaults and the required values in your [`tsconfig.json` file](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html).
+Next, rename any file to be a TypeScript file (e.g. `src/index.js` to `src/index.tsx`) and **restart your development server**!
 
 Type errors will show up in the same console as the build one.
 
-We recommend using [VSCode](https://code.visualstudio.com/) for a better integrated experience.
-
 To learn more about TypeScript, check out [its documentation](https://www.typescriptlang.org/).
+
+> Note: We recommend using [VSCode](https://code.visualstudio.com/) for a better integrated experience.
+
+> Note: Constant enum and namespaces are not supported.