add some basic kopia documentation

[weshayutin]

Basic connection and commands Pointer to doc Launch must-gather w/ kopia client

Why the changes were made

No real kopia tips in our repo

How to test the changes made

READ and try :)

[openshift-ci[bot]]

@weshayutin: all tests passed!

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[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kaovilai, mpryc, weshayutin

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