Codemods onboarding doc

[mfrances17]

[mfrances17]

Draft version of the codemods onboarding document is currently available here, for viewing and commenting:
https://docs.google.com/document/d/1MHRpSiSCN9fmdlZIIHnu6tqpdnLcADAlVoeUFG6JW-g

Once reviewed, I'll move it to the UXD development team's Product Onboarding Docs drive.

[mfrances17]

Final draft is now available on UXD Development Team's GDrive here:
https://docs.google.com/document/d/1MHRpSiSCN9fmdlZIIHnu6tqpdnLcADAlVoeUFG6JW-g