added turtles to concepts

doc/Concepts.md

@@ -120,3 +120,39 @@ In order for you program to be used it needs to be registered in the `BinStore`
 
 You can imagine the whole runtime like the event loop is JS. The `EndOfLoop` class is used to register callbacks that are called at the end of the loop.
 This is like the `setTimeout(0, callback)` in JS. 
+
+# Turtle Thread 
+
+Computercraft is mostly event-based. Listening to `Coroutine.yield()` waits for events with an option parameter for filtering events.
+The problem with turtle arises when we call turtle functions like `move` or `place`. These functions wait internally for 
+the operation to finish with a `Coroutine.yield("turtle_response")` call. There  is no way to prevent this. So in order to keep the main loop from 
+being blocked, we run all the turtle code in a separate thread. 
+
+There are no real threads in Lua, but we can create a coroutine for the turtles. Lua now switches between the main thread and the turtle thread. 
+Switching occurs when a `turtle_response` events is fired. This will be forwarded to the turtle thread. Once the turtle thread has run its code 
+and waits for the turtle operation to finish, we switch back to the main thread. The main thread is running normally until a `turtle_response` fires 
+and the circle repeats.
+
+Be aware that no one is stopping you from running turtle commands in the main thread. 
+
+See `KernelEvents.hx` for more. 
+
+## Using Turtle threads
+
+Example: 
+
+```haxe
+// In the context of a process
+
+if (!handle.claimTurtleMutex()) {
+    Log.warn("Failed to claim turtle thread");
+    return;
+}
+
+// Btw. no one is stopping you from calling this without claiming the mutex.
+TurtleMutex.runInTThread(() -> {
+    while(true){
+        Turtle.turnLeft();
+    }
+});
+```