Create high-level legend object

[jsoconno]

Is your feature request related to a problem? Please describe.
As a user, I would like a Legend object that was optimized for providing details about specific colors, icons, etc. and what they mean in the context of the diagram.

Describe the solution you'd like
Create a custom Legend class that allows for inputs and automatically generates a container with text inside at the bottom on the graph (or possibly the ability to specify a position).

Describe alternatives you've considered
Just having users get creative themselves and create a legend. Might not be too intuitive and would probably just result in this request eventually anyway.

Additional context
None.