interfaces and networks: update and cleanup doc

[nirdothan]

rearrange sections such that reading through would be easier, mainly by moving most restiriction and limitations to the bottom. Main sections are: Networks, Interfcaes. Security, Limitations and Known Issues, Additional Notes Later on links will be added from the sections in the top to their limitations in the bottom

What this PR does / why we need it:
The doc is cluttered and outdated, this PR attempts to modernize it, clean it up and make it easier for users to read through

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:

Checklist

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• 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
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• 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

[kubevirt-bot]

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[nirdothan]

/cc @EdDev