Fix Selected Permissions overview

[Jed Laundry (jlaundry)]

When trying to add SharePoint Selected Permissions to an application, we struggled, as we found:

• It was unclear that these APIs are only available via the beta version
• That the displayName attribute is now required when assigning permissions

This short PR clarifies these points.

---

Important

The following guidance is for Microsoft employees only. Community contributors can ignore this message; our content team will manage the status.

After you've created your PR, expand this section for tips and additional instructions.

• do not merge is the default PR status and is automatically added to all open PRs that don't have the ready to merge label.
• Add the ready for content review label to start a review. Only PRs that have met the minimum requirements for content review and have this label are reviewed.
• If your content reviewer requests changes, review the feedback and address accordingly as soon as possible to keep your pull request moving forward. After you address the feedback, remove the changes requested label, add the review feedback addressed label, and select the Re-request review icon next to the content reviewer's alias. If you can't add labels, add a comment with #feedback-addressed to the pull request.
• After the content review is complete, your reviewer will add the content review complete label. When the updates in this PR are ready for external customers to use, replace the do not merge label with ready to merge and the PR will be merged within 24 working hours.
• Pull requests that are inactive for more than 6 weeks will be automatically closed. Before that, you receive reminders at 2 weeks, 4 weeks, and 6 weeks. If you still need the PR, you can reopen or recreate the request.

For more information, see the Content review process summary.

[learn-build-service-prod]

Learn Build status updates of commit 717d774:

✅ Validation status: passed

File	Status	Preview URL	Details
concepts/permissions-selected-overview.md	✅Succeeded

For more details, please refer to the build report.

[Danipocket]

Jed Laundry (@jlaundry), are you a MSFTE? I need to validate some things. Thanks!

[Jed Laundry (jlaundry)]

Danipocket I'm not, but you can find more info and my contact details in support case 2511260030008384

[learn-build-service-prod]

Learn Build status updates of commit 2dd3b34:

✅ Validation status: passed

File	Status	Preview URL	Details
concepts/permissions-selected-overview.md	✅Succeeded

For more details, please refer to the build report.

[Regan Downer (v-regandowner)]

Patrick Rodgers (@patrick-rodgers)

Can you review the proposed changes?