Document the current DEP process about deps

[jacobian]

Indeed, I was one of the um-and-err-ers -- but I now think that having them be fixed static documents cause problems for no real benefit. But yeah, we should clarify -- in an updated DEP 1. We can have the conversation in that PR or on the mailing list/forum etc.

[jacobian]

Super agree. I've wanted to work on this for a bit, but may or may not get around to it anytime soon. If someone wanted to work on a draft, though, I'd 100% have time to review and sort of shepherd it through. Feel free to @ me in a pull request if anyone works on that.

FWIW: I don't think we have to keep DEPs frozen in time. I think my approach would be to update DEP 1 and DEP 10 with the changes, so that DEP 1 becomes the high level "how DEPs work", DEP 10 describes the Steering Council, and DEP 12 is a historical document describing the changes. (But I'm open to other approaches here too.)

[carltongibson]

FWIW: I don't think we have to keep DEPs frozen in time. ...

There was some umm-ing and err-ing about this when discussing DEP 12 — Are they living documents, or historical records? (I have no great opinion, but clarifying would help.)