ax(node): replace prose comment with usage examples on isJSON

AX Principle 2: comments must show how to call the function, not
restate what the type signature already says.

Co-Authored-By: Charon <charon@lethean.io>

pkg/node/bundle.go

@@ -196,7 +196,8 @@ func calculateChecksum(data []byte) string {
 	return hex.EncodeToString(hash[:])
 }
 
-// isJSON checks if data starts with JSON characters.
+// if isJSON(bundle.Data) { return bundle.Data, nil } // skip decrypt for plain profiles
+// if isJSON(content) { mode = 0644 } else { mode = 0755 } // executable unless JSON
 func isJSON(data []byte) bool {
 	if len(data) == 0 {
 		return false