Update role assignment limit and add new portal screen

[Vincent Misson (vmisson)]

This pull request updates the documentation to reflect a change in the maximum number of role assignments allowed per Azure subscription. The limit has been increased.

• Documentation update:
  • Increased the stated maximum number of role assignments per subscription from 4,000 to 5,000 in the role-assignments-list-portal.md file.

[prmerger-automator]

Vincent Misson (@vmisson) : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change. Robert Lyon (@rolyon)

[prmerger-automator]

Vincent Misson (@vmisson) : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change. Robert Lyon (@rolyon)

[learn-build-service-prod]

Learn Build status updates of commit f7ad219:

✅ Validation status: passed

File	Status	Preview URL	Details
articles/role-based-access-control/media/role-assignments-list-portal/access-control-role-assignments-chart.png	✅Succeeded
articles/role-based-access-control/role-assignments-list-portal.md	✅Succeeded

For more details, please refer to the build report.

[prmerger-automator]

PRMerger Results

Issue	Description
Image File	This PR added or updated an image file(s).

[Regan Downer (v-regandowner)]

Precious Mwongera (@mwongerapk)

Can you review the proposed changes?

IMPORTANT: When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
@MicrosoftDocs/public-repo-pr-review-team