add notes for root paths and binary support

Author: jeremydaly

README.md

@@ -454,3 +454,9 @@ Simply create one `{proxy+}` route that uses the `ANY` method and all requests w
 
 ## Contributions
 Contributions, ideas and bug reports are welcome and greatly appreciated. Please add  [issues](https://github.com/jeremydaly/lambda-api/issues) for suggestions and bugs reports.
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+## NOTES
+In order for "root" path mapping to work, you need to also create an `ANY` route for `/` in addition to your `{proxy+}` route.
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+To enable binary support, you need to add `*/*` under Binary Media Types in API Gateway > APIs > [your api] -> Settings.