Update RELEASE_NOTES.md

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

RELEASE_NOTES.md

@@ -8,6 +8,8 @@
 
 - Upgrade to microgrid API v0.15.1.  If you're using any of the lower level microgrid interfaces, you will need to upgrade your code.
 
+- The `BatteryPool.power_bounds` method now streams inclusion/exclusion bounds.  The bounds are now represented by `Power` objects and not `float`s.
+
 ## New Features
 
 <!-- Here goes the main new features and examples or instructions on how to use them -->