Add note about url encoding (#368)

* Add note about url encoding

* Add link to AWS Documentation

* Adjust the wording based on comments

* Point to official documentation

sigv4-signing/README.md

@@ -52,8 +52,11 @@ Connected (press CTRL+C to quit)
 
 ## Troubleshooting
 
+Please refer to the AWS documentation on troubleshooting: https://docs.aws.amazon.com/IAM/latest/UserGuide/signature-v4-troubleshooting.html
+
 If you are experiencing a `400` error:
 * The URL is invalid. Check the following:
+* Make sure the query paramters are made URL-safe (URL encoding): https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html
 * Ensure that the endpoint used matches the role you are connecting as. The `uri`/`wssUri` for your signaling channel is different depending on `role` specified when making the [GetSignalingChannelEndpoint](https://docs.aws.amazon.com/kinesisvideostreams/latest/dg/API_GetSignalingChannelEndpoint.html) API request.
 * If [connecting as viewer](https://docs.aws.amazon.com/kinesisvideostreams-webrtc-dg/latest/devguide/kvswebrtc-websocket-apis-1.html), ensure that the value for the `X-Amz-ClientId` query parameter does not begin with `AWS_`.