OWNERS: Configure Prow with approver and reviewer information

Most of the folks I've listed here are under Aaron in Red Hat, with
Yifan being the installer lead.  I've also included Alex and Clayton,
who are higher up in Red Hat but still members of
@openshift/installer.  I'm guessing about roles, but we can always
adjust later as we see fit.

Approvers can also /lgtm [1], so there's no need to list them under
'reviewers' as well.

The docs link in OWNERS is from [2].

While updating CONTRIBUTING.md to mention OWNERS (using wording based
on [3]), I've also:

* Added a line to make it clear that filing issues is helpful to (for
  folks who don't have the time or inclination to work up a PR).
* Turned the unordered list into an ordered list.  These entries
  happen sequentially, and an ordered list makes that more obvious.
* Made "below" a link, to make finding the referenced content more
  convenient.
* Shuffled words in the commit message format title to make it
  shorter.

The references to 'make structure-check' are stale since d61abd48 (*:
cleanup bazel rules, 2018-03-26, coreos/tectonic-installer#3137), but
I've left fixing that to follow-up work.

[1]: 4c0c2e9e65/contributors/guide/owners.md (quirks-of-the-process)
[2]: https://github.com/kubernetes/kubernetes-template-project/pull/15
[3]: 16f1588e6d/CONTRIBUTING.md (L10)

CONTRIBUTING.md

@@ -39,19 +39,21 @@ Due to their public nature, GitHub and mailing lists are not appropriate places
 
 ### Contribution Flow
 
-This is a rough outline of what a contributor's workflow looks like:
+Anyone may [file issues][new-issue].
+For contributors who want to work up pull requests, the workflow is roughly:
 
-- Create a topic branch from where you want to base your work (usually master).
-- Make commits of logical units.
-- Make sure your commit messages are in the proper format (see below).
-- Push your changes to a topic branch in your fork of the repository.
-- Make sure the tests pass, and add any new tests as appropriate.
-- Please run this command before submitting your pull request:
+1. Create a topic branch from where you want to base your work (usually master).
+2. Make commits of logical units.
+3. Make sure your commit messages are in the proper format (see [below](#commit-message-format)).
+4. Push your changes to a topic branch in your fork of the repository.
+5. Make sure the tests pass, and add any new tests as appropriate.
+6. Please run this command before submitting your pull request:
     ```sh
     make structure-check
     ```
-- Note that a portion of the docs and examples are generated and that the generated files are to be committed by you. `make structure-check` checks that what is generated is what you must commit.
-- Submit a pull request to the original repository.
+    Note that a portion of the docs and examples are generated and that the generated files are to be committed by you. `make structure-check` checks that what is generated is what you must commit.
+7. Submit a pull request to the original repository.
+8. The [repo owners](OWNERS) will respond to your issue promptly, following [the ususal Prow workflow][prow-review].
 
 Thanks for your contributions!
 
@@ -63,7 +65,7 @@ Tectonic Installer includes syntax checks on the Terraform templates which will
 
 Use `make structure-check` to identify files that don't meet the canonical format and style. Then, use `terraform fmt` to align the template syntax, if necessary.
 
-## Format of the Commit Message
+## Commit Message Format
 
 We follow a rough convention for commit messages that is designed to answer two
 questions: what changed and why. The subject line should feature the what and
@@ -98,3 +100,5 @@ git tools.
 [tf-doc]: https://www.terraform.io/docs/index.html
 [golang-style]: https://github.com/golang/go/wiki/CodeReviewComments
 [disclosure]: https://coreos.com/security/disclosure/
+[new-issue]: https://github.com/openshift/installer/issues/new
+[prow-review]: https://github.com/kubernetes/community/blob/master/contributors/guide/owners.md#the-code-review-process

OWNERS

@@ -0,0 +1,11 @@
+# See the OWNERS docs: https://git.k8s.io/community/contributors/guide/owners.md
+
+approvers:
+  - aaronlevey
+  - crawford
+  - smarterclayton
+  - yifan-gu
+reviewers:
+  - abhinavdahiya
+  - vikramsk
+  - wking