Updated Bag of Tricks (markdown)

Bag-of-Tricks.md

@@ -24,6 +24,70 @@ for(int led : root["leds"].asArray()) {
 
 See issue [#246](https://github.com/bblanchon/ArduinoJson/issues/246)
 
+## Nested array in a nested array
+
+Imagine you need to generate the following JSON:
+
+```json
+{
+  "value1": "x",
+  "value2": [
+    [
+      "Yes",
+      "No"
+    ],
+    [
+      "Maybe"
+    ]
+  ]
+}
+```
+
+The canonical way to do this is:
+
+```c++
+JsonObject& root = jsonBuffer.createObject();
+
+root["value1"] = "x";
+JsonArray& value2 = root.createNestedArray("value2");
+
+JsonArray& yesno = value2.createNestedArray();
+yesno.add("Yes");
+yesno.add("No");
+
+JsonArray& maybe = value2.createNestedArray();
+maybe.add("Maybe");
+```
+
+It's also possible to create the arrays and then put them in the object:
+
+```c++
+JsonObject& root = jsonBuffer.createObject();
+JsonObject& value2 = jsonBuffer.createArray();
+JsonObject& yesno = jsonBuffer.createArray();
+JsonObject& maybe = jsonBuffer.createArray();
+
+root["value1"] = "x";
+root["value2"] = value2;
+value2.add(yesno);
+yesno.add("Yes");
+yesno.add("No");
+value2.add(maybe);
+maybe.add("Maybe");
+```
+
+But it's a little less efficient in term of CPU and memory.
+
+Lastly, it's possible to manually encode the nested array with an undocumented feature:
+
+```c++
+JsonObject& root = jsonBuffer.createObject();
+root["value1"] = "x";
+root["value2"] = ArduinoJson::Internals::Unparsed("[[\"Yes\",\"No\"],[\"Maybe\"]");
+```
+
+See issue [#252](https://github.com/bblanchon/ArduinoJson/issues/252)
+
 ## Buffered output:
 
 Here is a proxy that will put bytes in a buffer before actually writing them to the destination: