Introduction / summary

[stuartpb]

This project needs a better high-level introduction than the current README, or the "oral history" roadmap on the Wiki.

It needs an announcement for the project's launch, as well as a better overall summary.

This is arguably the most important thing blocking an actual launch of v0.1.0, more than having unreviewed profiles or inconsistent structures, and should be regarded as a high priority as the end of the month approaches.

[stuartpb]

Okay, so... it's true that this is blocking a "launch" of v0.1.0, but it's not blocking the actual implementation of v0.1.0, so I'm moving it to v0.2.0, and let's all just hope it's taken care of by then.