Use ESDoc tags to document API client

[OrdinaryJellyfish]

The usage in the README is great for basic things, and for getting started, but there's a lot more in the API client that could be used. Currently (afaik) those methods are undocumented. However, I would suggest adding ESDoc tags to allow IDEs such as Visual Studio Code to offer documentation for required parameters and a quick description on each method when you're writing your code. ESDoc tags is a great way to improve understanding when you're writing code for me, and I think this library should totally use it (manually reading code to see what it does and how to use it is boring).

[bcomnes]

I support the idea!