Table of contents on events page in non-obvious position

[jchristgit]

As pointed out in #1363:

The Table of Contents is currently located to the bottom right of a typical browser screen. A keyboard user also must tab through two sections (“Events” and “Previous Events”) to reach it.

It could be more helpful for the table of contents to be near the top of the page, as well as being easily reachable through keyboard navigation.