Fix screen reader issues

[jessiehuff]

This collection of issues is a bunch of easy fixes that will help the screen reader experience quite a bit. Some of these are documentation/demo issues but are still important to show consumers the correct way to do it.

Testing tool	Issue	Type	URL	Specific Location	Suggested Solution
VO	Headings skip level (1 > 3 > 5)	Structure	all	Page and card headings	Headings should go in sequential order and convey structure
VO	Show prerequisites buttons should be unique	Labeling	all	preqs button	They should make sense out of context (i.e. "Show {title} prereqs")
VO	Status select should have a label	Labeling	https://quickstarts.netlify.app/quickstarts-props	Status select/dropdown	Should have some kind of label ("Status"), currently just expanded and collapsed button