Add description of version number in JSON doc (#256)
Add description of version number in JSON doc (#256)

The JSON file now includes a version number (under __meta__.version)
added by the compiler. However bmv2 does not perform any version check
as of today.
p4lang/behavioral-model,hanw/behavioral-model,hanw/behavioral-model,hanw/behavioral-model,p4lang/behavioral-model,p4lang/behavioral-model,p4lang/behavioral-model,hanw/behavioral-model,hanw/behavioral-model,p4lang/behavioral-model