Update release notes

Signed-off-by: Sahas Subramanian <sahas.subramanian@proton.me>

Author: shsms

RELEASE_NOTES.md

@@ -6,7 +6,8 @@
 
 ## Upgrading
 
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+- `LatestValueCache` now closes the receiver when it is stopped.
+- Fetching values from stopped `LatestValueCache` instances is now disallowed.
 
 ## New Features