Update Release Notes

Signed-off-by: camille-bouvy-frequenz <[email protected]>

Author: camille-bouvy-frequenz

RELEASE_NOTES.md

@@ -14,6 +14,7 @@
 * Extra validation check to ensure the quantity and price are within the allowed bounds.
 * Add more edge cases to the integration tests.
 * Add idiomatic string representations for `Power` and `Price` classes.
+* Add support for timeouts in the gRPC function calls
 
 ## Bug Fixes