[MAINTENANCE] Accessibility fixes: Homepage - "See How Easy It Is" H2

[adambuttrick]

Service/repository
EZID UI

Describe the current state/issue
The text "See How Easy It Is" on the home page is not properly formatted as an H2 heading element. Part of accessibility fixes on #546.

Describe the desired state/solution
Update the "See How Easy It Is" to be an H2 tag (<h2>).

[adambuttrick]

Included with https://github.com/CDLUC3/ezid/pull/786/files.