Change key colors to be contrast compliant

[erinchambers]

The yellow color we use in the key is too light to meet accessibility standards; it only has half the color contrast ratio we need to have for the upcoming ADA Title II deadline. The things we'll need to change are

• dotted underlines
• text color for passage deleted by overwritten added text
• archivist note (gray is also too light)

I drew up some suggestions today but we'll want to talk with the PIs before making any changes.