Create a new data submission guide page utilizing existing MD files/repo

[maxsibilla]

We want to create a new data submission page in the documents website that will live here: https://docs.sennetconsortium.org/data-submission

Another team has already created MD files with the information regarding data submission: https://github.com/hubmapconsortium/data_submission_guide

• [x] Fork the existing repo to X Atlas Consortia
• [x] Create a unique table of contents for this page that will link out to each section. Should look like this

[libpitt]

Note had to add

---
layout: default
---

to each md file in order to see it rendered locally in the docker container that mimics GH pages. I may have seen it work without the tag when on the actual GH pages server, but I am not sure.

Due to the name of the files, the url path names may not be the most SEO friendly.