docs: add missing docs

ref: N25B-115

src/control_backend/schemas/belief_list.py

@@ -16,4 +16,10 @@ class BeliefList(BaseModel):
 
 
 class GoalList(BaseModel):
+    """
+    Represents a list of goals, used for communicating multiple goals between agents.
+
+    :ivar goals: The list of goals.
+    """
+
     goals: list[BaseGoal]