Add help files for descriptions

Includes marked up model diagram and a general FAQ for RMLands that should help reviewers understand what they are looking at. KM edited FAQ document included here for backup but the primary document is the one without that suffix.

	new file:   Model Diagram Cheat Sheet.pdf
	new file:   Model Diagram Cheat Sheet.svg
	new file:   RMLands Landcover Type Descriptions FAQ kmedit.docx
	new file:   RMLands Landcover Type Descriptions FAQ.docx