Clarify that we're using button indices, not using gamepad button names

src/joystick/hidapi/SDL_hidapi_xboxone.c

@@ -495,7 +495,7 @@ HIDAPI_DriverXboxOne_HandleStatePacket(SDL_Joystick *joystick, hid_device *dev,
         }
 
         if (ctx->last_state[paddle_index] != data[paddle_index]) {
-            int nButton = SDL_CONTROLLER_BUTTON_MISC1 + ctx->has_share_button;
+            int nButton = SDL_CONTROLLER_BUTTON_MISC1 + ctx->has_share_button; /* Next available button */
             SDL_PrivateJoystickButton(joystick, nButton++, (data[paddle_index] & button1_bit) ? SDL_PRESSED : SDL_RELEASED);
             SDL_PrivateJoystickButton(joystick, nButton++, (data[paddle_index] & button2_bit) ? SDL_PRESSED : SDL_RELEASED);
             SDL_PrivateJoystickButton(joystick, nButton++, (data[paddle_index] & button3_bit) ? SDL_PRESSED : SDL_RELEASED);
@@ -760,10 +760,11 @@ HIDAPI_DriverXboxOneBluetooth_HandleStatePacketV2(SDL_Joystick *joystick, hid_de
         }
 
         if (ctx->last_state[paddle_index] != data[paddle_index]) {
-            SDL_PrivateJoystickButton(joystick, SDL_CONTROLLER_BUTTON_MISC1 + 0, (data[paddle_index] & button1_bit) ? SDL_PRESSED : SDL_RELEASED);
-            SDL_PrivateJoystickButton(joystick, SDL_CONTROLLER_BUTTON_MISC1 + 1, (data[paddle_index] & button2_bit) ? SDL_PRESSED : SDL_RELEASED);
-            SDL_PrivateJoystickButton(joystick, SDL_CONTROLLER_BUTTON_MISC1 + 2, (data[paddle_index] & button3_bit) ? SDL_PRESSED : SDL_RELEASED);
-            SDL_PrivateJoystickButton(joystick, SDL_CONTROLLER_BUTTON_MISC1 + 3, (data[paddle_index] & button4_bit) ? SDL_PRESSED : SDL_RELEASED);
+            int nButton = SDL_CONTROLLER_BUTTON_MISC1; /* Next available button */
+            SDL_PrivateJoystickButton(joystick, nButton++, (data[paddle_index] & button1_bit) ? SDL_PRESSED : SDL_RELEASED);
+            SDL_PrivateJoystickButton(joystick, nButton++, (data[paddle_index] & button2_bit) ? SDL_PRESSED : SDL_RELEASED);
+            SDL_PrivateJoystickButton(joystick, nButton++, (data[paddle_index] & button3_bit) ? SDL_PRESSED : SDL_RELEASED);
+            SDL_PrivateJoystickButton(joystick, nButton++, (data[paddle_index] & button4_bit) ? SDL_PRESSED : SDL_RELEASED);
         }
     }