Updated readme with Web Worker browser support information (developit#14)

Author: MattSidor

README.md

@@ -48,6 +48,21 @@ console.log(await getName('developit'))
 
 [🔄 **Run this example on JSFiddle**](https://jsfiddle.net/developit/mf9fbma5/)
 
+## Browser support
+
+Thankfully, Web Workers have been around for a while and [are broadly supported](https://caniuse.com/#feat=webworkers) by Chrome, Firefox, Safari, Edge, and Internet Explorer 10+.
+
+If you still need to support older browsers, you can just check for the presence of `window.Worker`:
+
+```js
+if (window.Worker) {
+    ...
+} else {
+    ...
+}
+```
+
+
 ## License & Credits
 
 > In addition to the contributors, credit goes to [@sgb-io](https://github.com/sgb-io) for his annotated exploration of Greenlet's source. This prompted a refactor that clarified the code and allowed for further size optimizations.