[DOC] Remove garbage text in lb_http_response_rewrite_rule.html.markdown

[salv-orlando]

This change remove some extra brackets in the "Importing" section

[vmwclabot]

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• Commit e03a99b6d3f5e35ed3b681155fe84cd3c2b85e99 must be signed by [email protected]

[annakhm]

need rebase to fix linter