add sidebar for v1.10 missed workload rebalancer doc

[chaosi-zju]

What type of PR is this?

/kind documentation

What this PR does / why we need it:

website of v1.10 should also have this doc, but now in v1.10 neither english version nor chinese version exist

so, add sidebar for v1.10 missed workload rebalancer doc.

Which issue(s) this PR fixes:

Fixes https://github.com/karmada-io/website/pull/639#issuecomment-2167306046

Special notes for your reviewer:

[chaosi-zju]

@XiShanYongYe-Chang @zhzhuang-zju

[zhzhuang-zju]

/lgtm

[chaosi-zju]

/cc @RainbowMango

[karmada-bot]

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