headers: Fix up bullet lists, now that wikiheaders.pl can handle them.

include/SDL_messagebox.h

@@ -148,9 +148,7 @@ extern DECLSPEC int SDLCALL SDL_ShowMessageBox(const SDL_MessageBoxData *message
  * `flags` may be any of the following:
  *
  * - `SDL_MESSAGEBOX_ERROR`: error dialog
- *
  * - `SDL_MESSAGEBOX_WARNING`: warning dialog
- *
  * - `SDL_MESSAGEBOX_INFORMATION`: informational dialog
  *
  * This function should be called on the thread that created the parent