Incomplete documentation in RequestValidator.cs

[JohnRosner]

Issue Summary

There is incomplete documentation to the public facing methods of RequestValidator.cs
Specifically the overloaded Validate method and ValidateBody method are missing docs. Link

Code Snippet

public bool Validate(string url, string body, string expected)

public bool ValidateBody(string rawBody, string expected)

Details

In addition to including documentation for these two methods, I'd like the following details clarified in the documentation:

• For the Validate function that takes in the body string, the bodySHA256 parameter should be included in the url
• the expected string is the Twilio signature from the request header. ("expected result" is not specific enough in my opinion)