skel: Plugins require a cniVersion in the NetConf

pkg/version/plugin.go

@@ -56,6 +56,7 @@ func PluginSupports(supportedVersions ...string) PluginInfo {
 	}
 }
 
+// PluginDecoder can decode the response returned by a plugin's VERSION command
 type PluginDecoder struct{}
 
 func (_ *PluginDecoder) Decode(jsonBytes []byte) (PluginInfo, error) {