Update release notes

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

Author: shsms

RELEASE_NOTES.md

@@ -6,7 +6,10 @@
 
 ## Upgrading
 
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+- The power manager now uses a new algorithm described [here](https://frequenz-floss.github.io/frequenz-sdk-python/v1.0-dev/user-guide/microgrid-concepts/#frequenz.sdk.microgrid--setting-power), and that leads to the following changes around how `propose_power` is called.
+
+    * The `microgrid.new_*_pool` methods no longer accept a `set_operating_point` parameter.
+    * Power proposals without bounds made through the `propose_power` methods would no longer limit the bounds for lower priority actors, but will shift their available bounds.  When bounds are specified, they will be used to restrict the bounds for lower priority actors.
 
 ## New Features