Fix broken headings in Markdown files

[bryant1410]

GitHub changed the way Markdown headings are parsed, so this change fixes it.

See bryant1410/readmesfix for more information.

Tackles bryant1410/readmesfix#1

[agarzola]

Thanks a lot, @bryant1410. I think we can do without the trailing # characters at the end of each heading. If you want to commit that change and push it to this PR, I’ll be happy to merge it.