Add prettier npm script and update command in docs (DefinitelyTyped#4…

…2365)

README.md

@@ -182,7 +182,7 @@ For a good example package, see [base64-js](https://github.com/DefinitelyTyped/D
 #### Common mistakes
 
 * First, follow advice from the [handbook](http://www.typescriptlang.org/docs/handbook/declaration-files/do-s-and-don-ts.html).
-* Formatting: Use 4 spaces. Prettier is set up on this repo, so you can run `npm run prettier -- --write path/to/package`. [When using assertions](https://github.com/SamVerschueren/tsd#assertions), add `// prettier-ignore` exclusion to mark line(s) of code as excluded from formatting:
+* Formatting: Use 4 spaces. Prettier is set up on this repo, so you can run `npm run prettier -- --write path/to/package/**/*.ts`. [When using assertions](https://github.com/SamVerschueren/tsd#assertions), add `// prettier-ignore` exclusion to mark line(s) of code as excluded from formatting:
     ```tsx
     // prettier-ignore
     const incompleteThemeColorModes: Theme = { colors: { modes: { papaya: { // $ExpectError

package.json

@@ -19,7 +19,8 @@
         "not-needed": "node scripts/not-needed.js",
         "update-codeowners": "node scripts/update-codeowners.js",
         "test": "node node_modules/types-publisher/bin/tester/test.js --run-from-definitely-typed",
-        "lint": "dtslint types"
+        "lint": "dtslint types",
+        "prettier": "prettier"
     },
     "devDependencies": {
         "dtslint": "latest",