updates to "what is this?"

[k8hertweck]

• changed title to "About"
• added separate sections for "Mission" and "People"
• included current participants with links and brief description

resolves #7

[k8hertweck]

Checking with @matsen @bcclaywell @barngab10 to make sure this looks ok!

[ghost]

@k8hertweck Looks good to me! It might be better if I am listed as Gabrielle. I don't show up on Centernet search under Gabi :)

[k8hertweck]

Great, updated your name, thanks!

[bcclaywell]

Looks good to me!