added K0 and K0Bar to known particles in sibyll

Processes/Sibyll/sibyll_codes.dat

@@ -17,6 +17,8 @@ Pi0 6 1 2
 # rho0 could interact but sibyll has no cross section/interaction length. was used for gamma had int
 Rho0 27 0 0
 K0Long 11 1 3
+K0 21 0 3
+K0Bar 22 0 3
 PiPlus 7 1 2
 PiMinus 8 1 2
 RhoPlus 25 0 0