keyboard: Note that enabling text input can also enable an IME

An active IME can potentially eat key events, particularly dead keys and parts of a compose sequence, so note this behavior in the documentation.

include/SDL3/SDL_keyboard.h

@@ -322,7 +322,8 @@ extern SDL_DECLSPEC SDL_Keycode SDLCALL SDL_GetKeyFromName(const char *name);
  *
  * Text input events are not received by default.
  *
- * On some platforms using this function shows the screen keyboard.
+ * On some platforms using this function shows the screen keyboard and/or activates
+ * an IME, which can prevent some key press events from being passed through.
  *
  * \param window the window to enable text input.
  * \returns true on success or false on failure; call SDL_GetError() for more
@@ -391,7 +392,8 @@ typedef enum SDL_Capitalization
  *
  * Text input events are not received by default.
  *
- * On some platforms using this function shows the screen keyboard.
+ * On some platforms using this function shows the screen keyboard and/or activates
+ * an IME, which can prevent some key press events from being passed through.
  *
  * These are the supported properties:
  *