Update README.md

Author: keithamus

README.md

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 # ariaNotify-polyfill
+
 Polyfill for the ARIA Notification API
+
+The goal of this library is to polyfill `ariaNotify` so that it can be used seamlessly across browsers that support the native functionality, and those that don't. This adds the `Element.prototype.ariaNotify` function if it does not exist, emulating the native functionaltiy.
+
+This is used in production on github.com.
+
+## Background 
+
+In browsers where `ariaNotify` is supported it will emit a notification event. In browsers where it isn't supported this library will create a "fake" element that is an aria-live region, insert it into the DOM, and modify the text content of the element to place the given message in, acheiving a similar effect to the native functionality.
+
+## Requirements
+
+This is only meant to be used in a browser context. It should not be used on the server. To install this you will likely need `npm`.
+
+```sh
+$ npm i @github/ariaNotify-polyfill
+```
+
+In your JavaScript you can introduce the polyfill using a "bare" import:
+
+```js
+import "@github/ariaNotify-polyfill"
+```
+
+Then continue to use `ariaNotify` as if it were supported everywhere. A small contrived example:
+
+```js
+button.ariaNotify("Saved")
+```
+
+## License 
+
+This project is licensed under the terms of the MIT open source license. Please refer to [MIT](./LICENSE.txt) for the full terms.
+
+## Maintainers 
+
+The @github/accessibiltiy and @github/primer teams maintain this library.
+
+## Support
+
+This library is provided "as is". Please feel free to file issues we offer no time frame for correspondance or resolution of any issues.
+
+## Acknowledgement
+
+Special thanks to Microsoft and the ARIA Working Group for making `ariaNotify` a possibility.