SDL_main.h: Cleanups in SDL_RegisterApp documentation.

There is an escaped pipe character, because this ends up in a Markdown table
on the wiki, and the wiki software (incorrectly, I think) sees the pipe inside
a code-block and thinks it's the end of the table cell if not escaped.

But this escape char looks wrong everywhere else.

Keeping the parameter table terse is always a good idea, so I moved the
detail out to the Remarks section, which doesn't have a problem with this
character appearing in the text.

include/SDL3/SDL_main.h

@@ -615,11 +615,12 @@ extern SDL_DECLSPEC int SDLCALL SDL_EnterAppMainCallbacks(int argc, char *argv[]
  * Most applications do not need to, and should not, call this directly; SDL
  * will call it when initializing the video subsystem.
  *
+ * If `name` is NULL, SDL currently uses `(CS_BYTEALIGNCLIENT | CS_OWNDC)`
+ * for the style, regardless of what is specified here.
+ *
  * \param name the window class name, in UTF-8 encoding. If NULL, SDL
  *             currently uses "SDL_app" but this isn't guaranteed.
- * \param style the value to use in WNDCLASSEX::style. If `name` is NULL, SDL
- *              currently uses `(CS_BYTEALIGNCLIENT \| CS_OWNDC)` regardless
- *              of what is specified here.
+ * \param style the value to use in WNDCLASSEX::style.
  * \param hInst the HINSTANCE to use in WNDCLASSEX::hInstance. If zero, SDL
  *              will use `GetModuleHandle(NULL)` instead.
  * \returns true on success or false on failure; call SDL_GetError() for more