Bluetooth: Mesh: Fix documentation of bt_mesh_input_string()

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
diff --git a/include/bluetooth/mesh/main.h b/include/bluetooth/mesh/main.h
index bc2faae..57306d0 100644
--- a/include/bluetooth/mesh/main.h
+++ b/include/bluetooth/mesh/main.h
@@ -143,7 +143,7 @@
  *  This is intended to be called after the bt_mesh_prov input callback
  *  has been called with BT_MESH_ENTER_STRING as the action.
  *
- *  @param string String.
+ *  @param str String.
  *
  *  @return Zero on success or (negative) error code otherwise.
  */