Add note about email read status in Microsoft 365 to changelog

Author: seanthegeek

CHANGELOG.md

@@ -11,6 +11,7 @@
 ### Improvements
 
 - Improve type hints across the library (Pylance/Pyright friendliness) and reduce false-positive linter errors.
+- Emails in Microsoft 365 are now marked read as they are read. This provides constancy with other mailbox types, and gives you a indication of when emails are being read as they are processed in batches.
 
 ### Compatibility / Dependencies