Update BDC Learn Page

[alvoght-renci]

@suejinkim20

Requesting updates to content on the Learn page of the BDC website. Not calling this a redesign since we are (mostly) keeping the original layout of the boxes. So, revamp and content updates. :)

Information on these choices and the mockup with new content is available here: https://docs.google.com/document/d/12X_xMHZizg4FbsqREII59MT0mKURboKdrp52YBslLh4/edit?usp=sharing

Only missing content is that links are not yet available for the "quick start" boxes (first 3 boxes on the page)

Note that we are also looking to include an Events section on this page, which would grab the nearest event from the Events page; if no event, then plain text with a "check back soon" message.

Since we've already discussed this work, hopefully this is enough info. Of course, reach out to me with questions!

[alvoght-renci]

@suejinkim20 not sure if you need it, but i also created a mockup of the actual page now (not just the Google doc format, haha). attached.

[mbwatson]

related to #332