Update mentor-focused materials

[shaunagm]

This guide needs to be updated. Should be very high level - 10 minutes max to read, likely more like 5 - with any real details on the wiki, and linked to there.

Get rid of the fun Javascripty thing and simply make the sections more prominent across the top of the page.

Notes:

• We should also add a brief instruction about not promoting your company at our events. (Hasn't been an issue so far, but some organizers have been worried about the ambiguity between talking about your career in open source vs using OSCTC as a recruiting tool, the former of which is great and the latter of which is not great.)