Update TW rake file and codeowners

What does this MR do and why?

Updates the TW codeowners rake file to reflect group changes per technical-writing#770 (closed).

Also ran the rake task to update CODEOWNERS.

I've made Evan the DRI for now, but will ask Niklas if it's possible to specify multiple owners.

Update: It's possible to specify multiple owners, so we've done that here.

FYI @eread @ashrafkhamis @dianalogan

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