Methods documentation

[loriabendroth]

@skbowd @lnowatzke and me:

• [ ] create document that explains why we did not use the "NO" data sources. This will be done on all NO in column E of the 00_Inventory spreadsheet. https://docs.google.com/spreadsheets/d/1xrr7L4g4_Dd2u5mSnHWVkV8QvlGHQUI_jdskEMvEgqw/edit#gid=0
• [ ] Complete methods for all blue YES data sources.

[lnowatzke]

• [ ] @lnowatzke Create the "didn't use" document