chore(docs) fix typo in btnmatrix.md
Fix typo.
@@ -56,7 +56,7 @@ An element of `ctrl_map` should look like `ctrl_map[0] = width | LV_BTNM_CTRL_NO
The number of elements should be equal to the number of buttons (excluding newlines characters).
### One check
-The "One check" feature can be enabled with `lv_btnmatrix_set_one_check(btnm, true)` to allow only one button to be checked at a time.
+The "One check" feature can be enabled with `lv_btnmatrix_set_one_checked(btnm, true)` to allow only one button to be checked at a time.
## Events
- `LV_EVENT_VALUE_CHANGED` Sent when a button is pressed/released or repeated after long press. The event parameter is set to the ID of the pressed/released button.
