Annotation lesson -- change to Annotation Hub?

[mistrm82]

Currently we use AnnotationDbi

We might want to change to AnnotationHub as we use in the DGE lesson, however this becomes a longer lesson since we need to describe the one-to-many mappings (as a list) issue for the Entrez Ids

Another option is to consider adding bioMart back in

[mistrm82]

Also, currently we link to this page for AnnotationHub: https://github.com/hbctraining/Training-modules/blob/master/DGE-functional-analysis/lessons/AnnotationHub.md

I think this should be updated to have code that walks through the same dataset used in-class to demonstrate how you would do it with AnnotationHub