Add a new silverpeas as a Docker official image

library/silverpeas

@@ -0,0 +1,4 @@
+# maintainer: Miguel Moquillon <[email protected]> (@mmoqui)
+
+latest: git://github.com/Silverpeas/docker-silverpeas-prod@b87b3bb7e28e61cd9d76262e897451e2b466d265
+6.0-alpha1: git://github.com/Silverpeas/docker-silverpeas-prod@b87b3bb7e28e61cd9d76262e897451e2b466d265