Update documentation for nginx-ingress-role RBAC.

[ejamesc]

What this PR does / why we need it: For the Role named nginx-ingress-role, endpoints no longer needs or has create and update permissions. This confused me, so I hope this helps!

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes confusing documentation that wasn't updated as part of a9168f2

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[k8s-reviewable]

This change is 

[ejamesc]

/assign @nicksardo

[codecov-io]

Codecov Report

Merging #2139 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2139   +/-   ##
=======================================
  Coverage   36.59%   36.59%           
=======================================
  Files          68       68           
  Lines        4837     4837           
=======================================
  Hits         1770     1770           
  Misses       2799     2799           
  Partials      268      268

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[aledbf]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, ejamesc

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[aledbf]

@ejamesc thanks!