Bring the Previous Data Releases / Release Notes labels into consistency with each other

[melissacline]

This was something pointed out by Alexis Morgan, genomics institute communications officer.

The menu option reads "Previous Data Releases", but it takes you to a page with the heading of "Release notes". For consistency, they should say the same thing. I suggested they both say "Previous Data Releases". She recommended that they both say "Data Releases" for conciseness. I think that's reasonable.

In the table in the "Data Releases" page, the leftmost column is labeled "Notes". That actually isn't the release note, but a link to the data release. So, let's replace "Notes" with "Release" as the column header.

Oh, the things that you learn when someone with fresh eyes comes to the site!