bracket spe & doc fix

Author: artivis

include/manif/impl/rn/RnTangent_base.h

@@ -202,6 +202,14 @@ struct RandomEvaluatorImpl<RnTangentBase<Derived>>
   }
 };
 
+template <typename Derived>
+struct BracketEvaluatorImpl<RnTangentBase<Derived>> {
+  template <typename TL, typename TR>
+  static typename Derived::Tangent run(const TL&, const TR&) {
+    return Derived::Tangent::Zero();
+  }
+};
+
 } // namespace internal
 } // namespace manif
 

include/manif/impl/tangent_base.h

@@ -363,7 +363,7 @@ struct TangentBase
    * @tparam _DerivedOther
    * @param a A Tangent object.
    * @param b A second Tangent object.
-   * @return @return LieAlg The Lie bracket [a,b] in vector form.
+   * @return The Lie bracket [a,b] in vector form.
    */
   template <typename _DerivedOther>
   static Tangent Bracket(