Transportation methodology explainer

[eroten]

Appendix/section within the transportation section on how the O/D method varies from MOVES/other methods used in the TPP.

ALSO: Update EPA NEI comparison section to clarify scopes and show a correlation instead of a direct comparison

DUE before July 12 so it may be included in the RDG as an appendix/technical memo

Originally posted by @eroten in #77 (comment)

[eroten]

This may just end up being an explanation of scopes and why they are different, plus how they should/can be reconciled

See fongGlobalProtocolCommunityScale2021 (https://ghgprotocol.org/sites/default/files/standards/GPC_Full_MASTER_RW_v7.pdf)

[eroten]

Closed with #104