Azure Active Directory - Credential Expiry Event documentation

[rahulkaukuntla]

What does this PR do?

Added a blurb under the Events section of the Azure Active Directory integration readme. This blurb discusses credential expiry events.

HOLD FOR GA: cc @rahulkaukuntla

Motivation

Additional Notes

Review checklist (to be filled by reviewers)

Release Checklist

• This code has automated tests
• Changes are being deployed behind a feature flag, if applicable
• Related changes to databases, devops, and/or consul-config have been made, if applicable
• These changes will work with production-level load
• I have a plan to verify that these changes are working as expected after deploy
• I have a plan for how to revert, rollback, or disable these changes if things are not working as expected
• If PR impacts documentation, docs team has been notified or a card has been created on the documentation triage
• If PR changes route(s), I have followed the process to update the routes in dogweb and k8s-resources.
• If the PR adds route(s), I have followed the API Production Readiness Review

See Also: https://github.com/DataDog/devops/wiki/Code-Workflow#deploying-to-production

Security Checklist

This PR creates, modifies, or deletes:

• API Routes: API routes, parameters and/or user permissions
• Authentication: Authentication mechanism (SAML, OAuth, password etc.)
• Credentials: Server side credentials or secrets in configuration/source code
• Cryptography: Cryptographic directives (encryption, hashing, certificates, signatures, random numbers, etc.)
• User Data: User input/sensitive content in URL params, logs, error messages, etc.
• None of the above

Unsure? Have a question? Request a review from @DataDog/security-design-and-guidance!

Additional Notes

[maycmlee]

Just a couple of small suggestions, but approving.