Fix warnings and add comments.

src/dynamics/joint/impulse_joint/impulse_joint.rs

@@ -3,14 +3,17 @@ use crate::math::{Real, SpacialVector};
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
 #[derive(Clone, Debug, PartialEq)]
-/// A joint attached to two bodies.
+/// An impulse-based joint attached to two bodies.
 pub struct ImpulseJoint {
     /// Handle to the first body attached to this joint.
     pub body1: RigidBodyHandle,
     /// Handle to the second body attached to this joint.
     pub body2: RigidBodyHandle,
 
+    /// The joint’s description.
     pub data: GenericJoint,
+
+    /// The impulses applied by this joint.
     pub impulses: SpacialVector<Real>,
 
     // A joint needs to know its handle to simplify its removal.