Content: about page additions

[agjohnson]

A few minor additions to the about page that I pushed off until next iteration on this page:

• Link some of the feature sections into more thorough website content pages and/or documentation
• Update some of the graphics on each section
• Add two columns under hosting to cover authentication and sharing, remove the authentication feature in the three column row, and move a hosting feature up from additional features to balance out the three column row.
  • Reuse the right column on the first row, discussing project types and privacy levels?
  • Mention teams and team authentication
  • Mention privacy levels
  • Describe SSO and link to a docs or a dedicated page. Probably it's own column really.