Add documentation that puts workflow steps into broader context.
See top of: https://code.usgs.gov/wma/nhgf/gfv2.0/-/blob/master/workspace/01_Gage_Selection.Rmd for style.
See top of: https://code.usgs.gov/wma/nhgf/gfv2.0/-/blob/master/workspace/01_Gage_Selection.Rmd for style.