Update service-limits.md for ACS Chat to introduce new limits

[tariqzafa700]

ACS Chat is going to add a new limit to throttle the usage of create chat thread and add chat participant APIs based on the requests from the same resource Id. Although the throttle limit exists on number of chat thread created per user but since a resource has the ability to create many such users, so we need to put a throttle limit at resource Id level.

[prmerger-automator[bot]]

@tariqzafa700 : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change.

[learn-build-service-prod[bot]]

Learn Build status updates of commit 121f29c:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
articles/communication-services/concepts/service-limits.md	:white_check_mark:Succeeded

For more details, please refer to the build report.

[v-dirichards]

@tophpalmer

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

[v-dirichards]

@tophpalmer Could you review this proposed update to your article and enter #sign-off in a comment if it's ready to merge?

Thanks!

[v-ccolin]

I sent an email to the content owner today.

@MicrosoftDocs/public-repo-pr-review-team