libvlc: document which function was used to set the user values

include/vlc/libvlc_dialog.h

@@ -176,7 +176,7 @@ libvlc_dialog_set_context(libvlc_dialog_id *p_id, void *p_context);
 
 /**
  * Return the opaque pointer associated with the dialog id
- *
+ * \see libvlc_dialog_set_context
  * @version LibVLC 3.0.0 and later.
  */
 LIBVLC_API void *

include/vlc/libvlc_media.h

@@ -737,6 +737,8 @@ LIBVLC_API void
  * Get media descriptor's user_data. user_data is specialized data
  * accessed by the host application, VLC.framework uses it as a pointer to
  * an native object that references a libvlc_media_t pointer
+ * 
+ * \see libvlc_media_set_user_data
  *
  * \param p_md media descriptor object
  */