add packageinfo for Geant4

documentation/packageinfo.txt

@@ -297,6 +297,17 @@
     "language" : "Other",
     "license" : "UNKNOWN",
   },
+  {
+    "name" : "Geant4",
+    "fullname" : "Geant4",
+    "description" : "a generic simulation toolkit",
+    "homepage" : "http://geant4.cern.ch/",
+    "contact" : "Gabriele Cosmo",
+    "project" : "true",
+    "category" : "Simulation",
+    "language" : "Cpp",
+    "license" : "Geant4 Software License",
+  },
 #  {
 #    "name" : "gcc",
 #    "fullname" : "gcc",