Update doc on label types for TooltipItem#6030

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simonbrunel merged 2 commits intochartjs:masterfrom

nagix:issue-6030

Feb 1, 2019

Commits on Jan 30, 2019

Update doc on label types for TooltipItem
nagix
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Commits on Jan 31, 2019

Set string values to TooltipItem.label/value and add tests
nagix
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