fix: Update annotation-use-case.md

[iHx-rainbow]

Correct a word spelling error

alibaba/higress pkg\ingress\kube\annotations\canary.go Line 28 Confirm the correct spelling of this annotation

const (
    enableCanary          = "canary"
    canaryByHeader        = "canary-by-header"
    canaryByHeaderValue   = "canary-by-header-value"
    canaryByHeaderPattern = "canary-by-header-pattern"
    canaryByCookie        = "canary-by-cookie"
    canaryWeight          = "canary-weight"
    canaryWeightTotal     = "canary-weight-total"

    defaultCanaryWeightTotal = 100
)

已在 higress 主项目 pkg\ingress\kube\annotations\canary.go 28行 确认此注解的正确拼写

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