fix tree error messages (remove "AVL")

src/rstd/collections/tree.rs

@@ -25,13 +25,13 @@ impl<E: Display> Display for TreeParseError<E> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             Self::Int(int_error) => {
-                write!(f, "failed to parse AVL tree height: {int_error}")
+                write!(f, "failed to parse tree height: {int_error}")
             }
             Self::Point(point_error) => {
-                write!(f, "failed to parse AVL node reference: {point_error}")
+                write!(f, "failed to parse node reference: {point_error}")
             }
             Self::Key(key_error) => {
-                write!(f, "failed to parse AVL node key: {key_error}")
+                write!(f, "failed to parse node key: {key_error}")
             }
         }
     }