I found a web page that said I could change the Heading for Column 10 to “Research notes” (sans quotes) and then use that field for bibliography annotations.
I could not, however, find a style for MLA 8 Annotated. Did I just miss it, is it not available, or will placing annotations in Column 10 then allow me to add that column to my bibliography why output?
Probably not exactly. It is possibly easier to follow the instructions in the original link you posted (which was related to Harvard, but would be similar) to add the research notes to your templates in MLA 8 I guess.