Merge pull request #1394 from srenatus/sr/docs/maintainers

update MAINTAINERS, mirror guidelines into dev doc

Documentation/dev-become-a-maintainer.md

+# Join the fun -- become a maintainer!
+
+If a person or their company uses dex, has demonstrated an understanding of this
+project (either by submitting PRs to dex or related projects such as Helm
+charts), and the ability to work productively with the community, that person
+can have write access to this repo. We want to be liberal with this privilege
+and enable companies using dex to have a voice in its development.
+
+The first 10 PRs by new maintainers must be approved by a maintainer from a
+different company.
+
+Access to https://quay.io/dexidp will be restricted to @srenatus, @rithujohn191
+and @ericchiang to prevent new maintainers from being able to unilaterally push
+images.
+
+If you would like access, please email @ericchiang at ericchiang@google.com
+stating your case or open a public issue. Come join the fun 😃

MAINTAINERS

 Rithu John <rithujohn191@gmail.com> (@rithujohn191)
 Eric Chiang <eric.chiang.m@gmail.com> (@ericchiang)
 Stephan Renatus <srenatus@chef.io> (@srenatus)
+Joel Speed <Joel.speed@hotmail.co.uk> (@JoelSpeed)