Two components of the boundary of \(\text \textbf{I}_3\). (Deux composantes du bord de \(\text \textbf{I}_3\)) Kompaktifizierung des Modulraumes \(M_ I(0,2)\) reeller 2-Instantonen auf \(S^ 4\). (On the compactification of the moduli space \(M_ I(0,2)\) of real 2-instantons on \(S^ 4)\) 