docs(windows-cilium): windows cilium plugin design

[mikeagun]

Description

Add documentation for windows cilium event observer plugin.

Related Issue

Checklist

• I have read the contributing documentation.
• I signed and signed-off the commits (git commit -S -s ...). See this documentation on signing commits.
• I have correctly attributed the author(s) of the code.
• I have tested the changes locally.
• I have followed the project's style guidelines.
• I have updated the documentation, if necessary.
• I have added tests, if applicable.

Screenshots (if applicable) or Testing Completed

N/A

Additional Notes

Documentation update only.