Document the library features!

[robertshepherdcpp]

So, there are a lot of features that are not documented in our README.md so I have made this issue. This is great for new commers as the code is simple and all you need to do is, follow the template:

Here is an example implementation of CLASS_NAME:

// temlate if there is one
struct CLASS_NAME
{
auto MEMBER_FUNCTION_NAME(); // no implementation

CLASS_NAME(); // constructor, again don't show the implementation.
}

Here is an example use of this feature:

CLASS_NAME class(); // just a quick example

So, all of that will go in the README.md please! You don't need to do all of it, any help will be appreciated!