DHH Accessible Conference Checklist CTA in best practices doc

[CathPag]

Once this PR is merged, I'll need some help adding a call to action to a checklist we created for event organizers in this doc. I created a mockup, but have no idea how to create that. @cjyabraham, could you help?

[cjyabraham]

Sure. So you want that mockup implementing somewhere on the Contribute site?

[CathPag]

Correct. On this page, under the first section. The other PR is merged, so we are good to go whenever you are ready.
Thank you!!

[cjyabraham]

Ok, how's this: #669