Update footer.html to include CoC

[ayhanxian]

Code of Conduct link in the footer for the pyopensci.org website in response to issue #396

[lwasser]

@all-contributors please add @ayhanxian for code, review

[allcontributors[bot]]

@lwasser

I've put up a pull request to add @ayhanxian! :tada:

[lwasser]

@ayhanxian it was so great to meet you at SciPy 🚀 Thank you again for this pr. i'm merging it which should also close the associated open issue!! Great job on the pull requests that you submitted during our sprints.