[7.6][docs] Backport: Clarify privileges required for the writer role (#15604)#15666

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dedemorton merged 1 commit intoelastic:7.6from dedemorton:backport_15604_7.6

Jan 21, 2020

+3-2

Commits on Jan 18, 2020

[docs] Clarify privileges required for the writer role (elastic#15604 )
dedemorton
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