[skip-ci] improve doc. Fix root-project#8051 (root-project#8207)

* [skip-ci] improve doc. Fix root-project#8051

* rephrasing

math/genvector/inc/Math/Vector2Dfwd.h

@@ -33,24 +33,40 @@ namespace ROOT {
 
       /**
          2D Vector based on the cartesian coordinates x,y in double precision
+
+       To use it add the line `#include <Vector2D.h>`
+
+       See the documentation on the DisplacementVector2D page.
       */
       typedef DisplacementVector2D< Cartesian2D<double>, DefaultCoordinateSystemTag > XYVector;
       typedef XYVector XYVectorD;
 
       /**
          2D Vector based on the cartesian coordinates x,y,z in single precision
+
+       To use it add the line `#include <Vector2D.h>`
+
+       See the documentation on the DisplacementVector2D page.
       */
       typedef DisplacementVector2D< Cartesian2D<float>, DefaultCoordinateSystemTag > XYVectorF;
 
 
       /**
          2D Vector based on the polar coordinates rho, phi in double precision.
+
+       To use it add the line `#include <Vector2D.h>`
+
+       See the documentation on the DisplacementVector2D page.
       */
       typedef DisplacementVector2D< Polar2D<double>, DefaultCoordinateSystemTag > Polar2DVector;
       typedef Polar2DVector Polar2DVectorD;
 
       /**
          2D Vector based on the polar coordinates rho, phi in single precision.
+
+       To use it add the line `#include <Vector2D.h>`
+
+       See the documentation on the DisplacementVector2D page.
       */
       typedef DisplacementVector2D< Polar2D<float>, DefaultCoordinateSystemTag > Polar2DVectorF;
 

math/genvector/inc/Math/Vector3Dfwd.h

@@ -36,40 +36,72 @@ namespace ROOT {
 
     /**
        3D Vector based on the cartesian coordinates x,y,z in double precision
+
+       To use it add the line `#include <Vector3D.h>`
+
+       See the documentation on the DisplacementVector3D page.
     */
     typedef DisplacementVector3D< Cartesian3D<double>, DefaultCoordinateSystemTag > XYZVector;
     /**
-       3D Vector based on the cartesian corrdinates x,y,z in single precision
+       3D Vector based on the cartesian coordinates x,y,z in single precision
+
+       To use it add the line `#include <Vector3D.h>`
+
+       See the documentation on the DisplacementVector3D page.
     */
     typedef DisplacementVector3D< Cartesian3D<float>, DefaultCoordinateSystemTag > XYZVectorF;
     typedef XYZVector XYZVectorD;
 
     /**
        3D Vector based on the eta based cylindrical coordinates rho, eta, phi in double precision.
+
+       To use it add the line `#include <Vector3D.h>`
+
+       See the documentation on the DisplacementVector3D page.
     */
     typedef DisplacementVector3D< CylindricalEta3D<double>, DefaultCoordinateSystemTag > RhoEtaPhiVector;
     /**
        3D Vector based on the eta based cylindrical coordinates rho, eta, phi in single precision.
+
+       To use it add the line `#include <Vector3D.h>`
+
+       See the documentation on the DisplacementVector3D page.
     */
     typedef DisplacementVector3D< CylindricalEta3D<float>, DefaultCoordinateSystemTag > RhoEtaPhiVectorF;
     typedef RhoEtaPhiVector RhoEtaPhiVectorD;
 
     /**
        3D Vector based on the polar coordinates rho, theta, phi in double precision.
+
+       To use it add the line `#include <Vector3D.h>`
+
+       See the documentation on the DisplacementVector3D page.
     */
     typedef DisplacementVector3D< Polar3D<double>, DefaultCoordinateSystemTag > Polar3DVector;
     /**
        3D Vector based on the polar coordinates rho, theta, phi in single precision.
+
+       To use it add the line `#include <Vector3D.h>`
+
+       See the documentation on the DisplacementVector3D page.
     */
     typedef DisplacementVector3D< Polar3D<float>, DefaultCoordinateSystemTag > Polar3DVectorF;
     typedef Polar3DVector Polar3DVectorD;
 
     /**
        3D Vector based on the cylindrical coordinates rho, z, phi in double precision.
+
+       To use it add the line `#include <Vector3D.h>`
+
+       See the documentation on the DisplacementVector3D page.
     */
     typedef DisplacementVector3D< Cylindrical3D<double>, DefaultCoordinateSystemTag > RhoZPhiVector;
     /**
        3D Vector based on the cylindrical coordinates rho, z, phi in single precision.
+
+       To use it add the line `#include <Vector3D.h>`
+
+       See the documentation on the DisplacementVector3D page.
     */
     typedef DisplacementVector3D< Cylindrical3D<float>, DefaultCoordinateSystemTag > RhoZPhiVectorF;
     typedef RhoZPhiVector RhoZPhiVectorD;

math/genvector/inc/Math/Vector4Dfwd.h

@@ -23,7 +23,7 @@ namespace ROOT {
   namespace Math {
 
 
-    // forward declaretions of Lorentz Vectors and type defs definitions
+    // forward declarations of Lorentz Vectors and type defs definitions
 
     template<class CoordSystem> class LorentzVector;
 
@@ -38,30 +38,50 @@ namespace ROOT {
 
     /**
        LorentzVector based on x,y,x,t (or px,py,pz,E) coordinates in double precision with metric (-,-,-,+)
+
+       To use it add the line `#include <Vector4D.h>`
+
+       See the documentation on the LorentzVector page.
     */
     typedef LorentzVector<PxPyPzE4D<double> > XYZTVector;
     // for consistency
     typedef LorentzVector<PxPyPzE4D<double> > PxPyPzEVector;
 
 
     /**
-     LorentzVector based on x,y,x,t (or px,py,pz,E) coordinates in float precision with metric (-,-,-,+)
+       LorentzVector based on x,y,x,t (or px,py,pz,E) coordinates in float precision with metric (-,-,-,+)
+
+       To use it add the line `#include <Vector4D.h>`
+
+       See the documentation on the LorentzVector page.
     */
     typedef LorentzVector< PxPyPzE4D <float> > XYZTVectorF;
 
 
     /**
        LorentzVector based on the x, y, z,  and Mass in double precision
+
+       To use it add the line `#include <Vector4D.h>`
+
+       See the documentation on the LorentzVector page.
     */
     typedef LorentzVector<PxPyPzM4D<double> > PxPyPzMVector;
 
     /**
        LorentzVector based on the cylindrical coordinates Pt, eta, phi and E (rho, eta, phi, t) in double precision
+
+       To use it add the line `#include <Vector4D.h>`
+
+       See the documentation on the LorentzVector page.
     */
     typedef LorentzVector<PtEtaPhiE4D<double> > PtEtaPhiEVector;
 
     /**
        LorentzVector based on the cylindrical coordinates pt, eta, phi and Mass in double precision
+
+       To use it add the line `#include <Vector4D.h>`
+
+       See the documentation on the LorentzVector page.
     */
     typedef LorentzVector<PtEtaPhiM4D<double> > PtEtaPhiMVector;