[React] FooterSlim includes an <h3> which could be confusing for screen readers

[sawyerh]

Mayflower version: @massds/mayflower-react" 10.0.0-alpha.2

The FooterSlim component includes an h3, which can result in inaccurate heading ordering, since there isn't a parent h2. This could be confusing to screen reader users who navigate by headings. A more accurate heading level would be an h2 (or no heading?)

[sawyerh]

Screenshot from Lighthouse related to this:

[clairesunstudio]

Thanks for noticing and submitting mayflower issues as always! Here's a PR for your review. Based on the conversation with @ygannett, we decided to go with removing the heading and using <div> in places of <section> in the Footer. Please review the linked PR.