Update release notes

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

RELEASE_NOTES.md

@@ -6,12 +6,12 @@
 
 ## Upgrading
 
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+- The SDK is now using the microgrid API client from [`frequenz-client-microgrid`](https://github.com/frequenz-floss/frequenz-client-microgrid-python/). You should update your code if you are using the microgrid API client directly.
 
 ## New Features
 
 <!-- Here goes the main new features and examples or instructions on how to use them -->
 
 ## Bug Fixes
 
-<!-- Here goes notable bug fixes that are worth a special mention or explanation -->
+- A bug was fixed where the grid fuse was not created properly and would end up with a `max_current` with type `float` instead of `Current`.