Add sig-observability charter

[machadovilaca]

What this PR does / why we need it:

Add sig-observability charter

Checklist

This checklist is not enforcing, but it's a reminder of items that could be relevant to every PR.
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:

NONE

[machadovilaca]

/cc @sradco @fabiand @assafad @avlitman @enp0s3 @iholder101

[avlitman]

This is great! small nit: maybe add a link to the best practices

[machadovilaca]

This is great! small nit: maybe add a link to the best practices

@avlitman in the template mentions we are not supposed list of specific code locations, the idea is just give a responsibility overview I think
https://github.com/kubevirt/community/blob/main/sig-TEMPLATE/sig-charter-template.md

[avlitman]

/lgtm

[sradco]

/lgtm

[fabiand]

/approve

Thanks!

[kubevirt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fabiand

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[fabiand]

Darn

@machadovilaca please also open a PR with an update to sigs.yaml in