Added an overload of prettyPrintTo()

JsonGenerator/JsonPrintable.cpp

@@ -10,12 +10,18 @@
 using namespace ArduinoJson::Generator;
 using namespace ArduinoJson::Internals;
 
-size_t JsonPrintable::printTo(char* buffer, size_t bufferSize)
+size_t JsonPrintable::printTo(char* buffer, size_t bufferSize) const
 {
     StringBuilder sb(buffer, bufferSize);
     return printTo(sb);
 }
 
+size_t JsonPrintable::prettyPrintTo(char* buffer, size_t bufferSize) const
+{
+    StringBuilder sb(buffer, bufferSize);
+    return prettyPrintTo(sb);
+}
+
 size_t JsonPrintable::prettyPrintTo(IndentedPrint& p) const
 {
     JsonPrettyPrint prettyPrint(p);