In README, mention that adding your name to "Definitions by" sends you notifications (#19751)

* In README, mention that adding your name to "Definitions by" sends you notifications

* Update README.md

README.md

@@ -88,6 +88,7 @@ First, [fork](https://guides.github.com/activities/forking/) this repository, in
 * `cd types/my-package-to-edit`
 * Make changes. Remember to edit tests.
 * You may also want to add yourself to "Definitions by" section of the package header.
+  - This will cause you to be notified (via your GitHub username) whenever someone makes a pull request or issue about the package.
   - Do this by adding your name to the end of the line, as in `// Definitions by: Alice <https://github.com/alice>, Bob <https://github.com/bob>`.
   - Or if there are more people, it can be multiline
   ```typescript
@@ -145,7 +146,7 @@ For a good example package, see [base64-js](https://github.com/DefinitelyTyped/D
     Example where it is not acceptable: `function parseJson<T>(json: string): T;`.
     Exception: `new Map<string, number>()` is OK.
 * Using the types `Function` and `Object` is almost never a good idea. In 99% of cases it's possible to specify a more specific type. Examples are `(x: number) => number` for [functions](http://www.typescriptlang.org/docs/handbook/functions.html#function-types) and `{ x: number, y: number }` for objects. If there is no certainty at all about the type, [`any`](http://www.typescriptlang.org/docs/handbook/basic-types.html#any) is the right choice, not `Object`. If the only known fact about the type is that it's some object, use the type [`object`](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-2.html#object-type), not `Object` or `{ [key: string]: any }`.
-* `var foo: string | any`: 
+* `var foo: string | any`:
     When `any` is used in a union type, the resulting type is still `any`. So while the `string` portion of this type annotation may _look_ useful, it in fact offers no additional typechecking over simply using `any`.
     Depending on the intention, acceptable alternatives could be `any`, `string`, or `string | object`.
 
@@ -297,7 +298,7 @@ When `dts-gen` is used to scaffold a scoped package, the `paths` property has to
       "@foo/bar": ["foo__bar"]
     }
 }
-``` 
+```
 
 
 #### The file history in GitHub looks incomplete.