doc: add more stuff to the group multibody

src/multibody/fwd.hpp

@@ -12,6 +12,11 @@
 namespace pinocchio
 {
 
+  /**
+   * \addtogroup multibody
+   * @{
+   */
+
   template<typename Scalar, int Options=0> struct FrameTpl;
 
   template<typename Scalar, int Options = 0, template<typename S, int O> class JointCollectionTpl = JointCollectionDefaultTpl>
@@ -19,11 +24,6 @@ namespace pinocchio
   template<typename Scalar, int Options = 0, template<typename S, int O> class JointCollectionTpl = JointCollectionDefaultTpl>
   struct DataTpl;
 
-  /**
-   * \addtogroup multibody
-   * @{
-   */
-
   typedef std::size_t Index;
   typedef Index JointIndex;
   typedef Index GeomIndex;