docs: add note about IE11 support when using as React component

resolves #809

README.md

@@ -185,6 +185,8 @@ You can also specify `onLoaded` callback which will be called each time Redoc ha
 />
 ```
 
+[**IE11 Support Notes**](docs/usage-with-ie11.md)
+
 ## The Docker way
 
 ReDoc is available as pre-built Docker image in official [Docker Hub repository](https://hub.docker.com/r/redocly/redoc/). You may simply pull & run it:

docs/usage-with-ie11.md

@@ -0,0 +1,24 @@
+# Usage With IE11
+
+
+## Standalone package
+
+IE11 is supported by default if you use ReDoc as a standalone package.
+
+## Usage as a React component
+
+If you use ReDoc as a React component you should include the following polyfills in your project:
+
+```js
+import 'core-js/es6/promise';
+import 'core-js/fn/array/find';
+import 'core-js/fn/object/assign';
+import 'core-js/fn/string/ends-with';
+import 'core-js/fn/string/starts-with';
+
+import 'core-js/es6/map';
+import 'core-js/es6/symbol';
+
+import 'unfetch/polyfill/index'; // or any other fetch polyfill
+import 'url-polyfill';
+```