Update release notes

Signed-off-by: Matthias Wende <[email protected]>

Author: matthias-wende-frequenz

RELEASE_NOTES.md

@@ -20,6 +20,8 @@ Another notable change is the microgrid API client being moved to its own [repos
 
 - PV power is now available from `microgrid.pv_pool().power`, and no longer from `microgrid.logical_meter().pv_power`.
 
+- The `frequenz-client-microgrid` has been bumped to v0.3 which supports reading reactive power metrics.
+
 ## New Features
 
 - `EVChargerPool`/`microgrid.ev_charger_pool()`: New `propose_power` and `power_status` methods have been added, similar to the `BatteryPool`.  These method interface with the `PowerManager` and `PowerDistributor`, which currently uses a first-come-first-serve algorithm to distribute power to EVs.