add tutorial docs about auto-completion for karmadactl

[zhzhuang-zju]

What type of PR is this? /kind documentation

What this PR does / why we need it: This document is intended to introduce how to use the auto-completion capability of karmadactl

Which issue(s) this PR fixes: Fixes #

Special notes for your reviewer:

[karmada-bot]

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[zhzhuang-zju]

/hold wait for #760