Add Certifications section

[nathen418]

Since this repo seems to be geared toward developers, technical people, etc. I thought it would be nice if there were a section on the page that could showcase industry certifications, as those are something that many people in the technology sphere have.

I modeled an example after the education section, and it would show up in that column something like this:

I added it to my personal fork of this repository a few months ago and decided that it would make a good contribution to the upstream repository.

Pull request: #234