Fix decrement button label in OnTheCanvas example component (#2432)

| **Before** | **After** |
| - | - |
| <img width="325" alt="Screenshot 2024-01-09 at 15 34 29"
src="https://github.com/tldraw/tldraw/assets/38284426/2e97723a-787f-4eba-9000-c72eb94974f1">
| <img width="325" alt="Screenshot 2024-01-09 at 15 34 11"
src="https://github.com/tldraw/tldraw/assets/38284426/5f1171b4-2d02-4d90-95de-cb4e58d9de09">
|

### Change Type

- [x] `documentation` — Changes to the documentation only[^2]

### Release Notes

- tiny bug fix, simply changing a label to match behaviour

apps/examples/src/examples/things-on-the-canvas/OnTheCanvas.tsx

@@ -31,7 +31,7 @@ function MyComponent() {
 				onPointerDown={stopEventPropagation}
 				onPointerMove={stopEventPropagation}
 			>
-				The count is {state}! <button onClick={() => setState((s) => s - 1)}>+1</button>
+				The count is {state}! <button onClick={() => setState((s) => s - 1)}>-1</button>
 			</div>
 			<div
 				style={{