Add release notes for previously merged changes

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

Author: shsms

RELEASE_NOTES.md

@@ -6,12 +6,32 @@
 
 ## Upgrading
 
+- `Sample` objects no longer hold `float`s, but rather `Quantity` or one of its subclasses, like `Power`, `Current`, `Energy`, etc. based on the type of values being streamed.
+
+  ```python
+  sample: Sample[Power] = await battery_pool.power.new_receiver().receive()
+  power: float = sample.value.as_watts()
+  ```
+
+- `BatteryPool.soc` now streams values of type `Sample[Quantity]`, and `BatteryPool.capacity` now streams values of type `Sample[Energy]`.
+
+  ```python
+  battery_pool = microgrid.battery_pool()
+  soc_sample: Sample[Quantity] = await battery_pool.soc.new_receiver().receive()
+  soc: float = soc_sample.value.base_value
+
+  capacity_sample: Sample[Energy] = await battery_pool.capacity.new_receiver().receive()
+  capacity: float = soc_sample.value.as_watt_hours()
+  ```
+
 <!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
 
 ## New Features
 
 - The logical meter has a new method that returns producer power, that is the sum of all energy producers.
 
+- `Quantity` types (`Power`, `Current`, `Energy`, `Voltage`) for providing type- and unit-safety when dealing with physical quantities.
+
 <!-- Here goes the main new features and examples or instructions on how to use them -->
 
 ## Bug Fixes