Actually add documentation

[mattleibow]

As SignaturePad is a relatively small project, and we aren't going to be getting an official documentation page on the MS docs website, we can just use XML comments in the code.

I hope to get all the docs in for v3.0, so if anyone is feeling generous or has extra time, you can just edit the docs directly from GitHub. Even if it is just the summary.

Only the public APIs need docs as that is all that is exported to the intellisense files.

Some examples:

Types (class, struct)

/// <summary>
/// [a simple description of what the class is/does]
/// eg: "Used to load objects from some data store."
/// </summary>
public class ObjectLoader { }

Methods

/// <summary>
/// [a simple description of what this method does and/or returns]
/// eg: "Returns the name of the object specified by the ID."
/// </summary>
/// <param name="paramName">[a short summary of this particular parameter] - eg: "The object's ID."]</param>
/// <returns>[what the returned value is - eg: "Returns the object's name."]</returns>
public string GetNameFromId(int paramName);

Properties (readonly)

/// <summary>
/// [a simple description of what this property gets]
/// eg: "Gets the ID of the objects."
/// </summary>
public int Id { get; }

/// <summary>
/// [a simple description of what this property gets and sets]
/// eg: "Gets or sets the ID of the objects."
/// </summary>
public int Id { get; set; }

[VladislavAntonyuk]

I think you should configure stylecop, fxcop or any other tool in resharper which will generate you documentation