Fix dox for namespaces

Eigen/src/Jacobi/Jacobi.h

@@ -255,13 +255,13 @@ void JacobiRotation<Scalar>::makeGivens(const Scalar& p, const Scalar& q, Scalar
 *   Implementation of MatrixBase methods
 ****************************************************************************************/
 
+namespace internal {
 /** \jacobi_module
   * Applies the clock wise 2D rotation \a j to the set of 2D vectors of cordinates \a x and \a y:
   * \f$ \left ( \begin{array}{cc} x \\ y \end{array} \right )  =  J \left ( \begin{array}{cc} x \\ y \end{array} \right ) \f$
   *
   * \sa MatrixBase::applyOnTheLeft(), MatrixBase::applyOnTheRight()
   */
-namespace internal {
 template<typename VectorX, typename VectorY, typename OtherScalar>
 void apply_rotation_in_the_plane(VectorX& _x, VectorY& _y, const JacobiRotation<OtherScalar>& j);
 }