owners, user-guide: set up owners from sigs

[dhiller]

What this PR does / why we need it:

Since we have the sigs formed for the several topics, let's establish ownership of the sections by each respective sig.

This PR adds and OWNERS_ALIASES file to capture the several aliases, copying from kubevirt/kubevirt. Also it adds OWNERS that refer to those sig groups, so that the groups can own the changes to the user-guide themselves.

Also it removes some users from the reviewers section who haven't shown
review activity for the last six months - this way we avoid assigning
them to the reviews and getting reviews stalled.

See https://kubevirt.devstats.cncf.io/d/46/pr-reviews-by-contributor?orgId=1&var-period=d7&var-repo_name=kubevirt%2Fuser-guide&var-reviewers=%22davidvossel%22&var-reviewers=%22rmohr%22&var-reviewers=%22stu-gott%22

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:
/cc @aburdenthehand @cwilkers @alicefr

Checklist

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Approvers are expected to review this list.

• Design: A design document was considered and is present (link) or not required
• PR: The PR description is expressive enough and will help future contributors
• Code: Write code that humans can understand and Keep it simple
• Refactor: You have left the code cleaner than you found it (Boy Scout Rule)
• Upgrade: Impact of this change on upgrade flows was considered and addressed if required
• Testing: New code requires new unit tests. New features and bug fixes require at least on e2e test
• Documentation: A user-guide update was considered and is present (link) or not required. You want a user-guide update if it's a user facing feature / API change.
• Community: Announcement to kubevirt-dev was considered

Release note:

[jean-edouard]

@dhiller will we setup a job to open update PRs when OWNERS_ALIASES changes in kubevirt/kubevirt?

[dhiller]

@dhiller will we setup a job to open update PRs when OWNERS_ALIASES changes in kubevirt/kubevirt?

Yeah, I think automation around this would make much sense - not yet sure what exactly we want to do around this. I'd say we store lists inside community repo and sync from there

[jean-edouard]

/approve
/hold
Holding to give this some time to be seen

[kubevirt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jean-edouard

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Needs approval from an approver in each of these files:

• OWNERS [jean-edouard]

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[alicefr]

/lgtm
Many thanks @dhiller for the quick PR!

[aburdenthehand]

/lgtm
Thanks for picking this up @dhiller

[dhiller]

/unhold

Noone has complained, so we seem to have reached silent consensus.