Complete steps 1 to 4 for new committers (driesm)

[driesm]

Summary

This should include the necessary changes to the doc tree.

Commit message:

Reviewed by: tbd (mentor)
Approved by: tbd (mentor)
Differential Revision: https://reviews.freebsd.org/D32889

[0mp]

Seems good, just make sure to review your commit with git log before pushing. Also, I guess that apart from

Reviewed by: tbd (mentor)
Approved by: tbd (mentor)
Differential Revision: https://reviews.freebsd.org/D32889

it would be nice to add a title to the commit message, of course :)

shared/contrib-committers.adoc

233

This file seems to be sorted by surnames so I assume that you put it into the right place :)