docs: heavy editing to make this happy with latest wikibridge.

The public headers saw lots of cleanups, backporting from SDL3 docs, and
merging with the wiki.

The markdown files in docs/README-*.md were converted to Unix endlines.

include/SDL_scancode.h

@@ -31,14 +31,14 @@
 #include "SDL_stdinc.h"
 
 /**
- *  \brief The SDL keyboard scancode representation.
+ * The SDL keyboard scancode representation.
  *
- *  Values of this type are used to represent keyboard keys, among other places
- *  in the \link SDL_Keysym::scancode key.keysym.scancode \endlink field of the
- *  SDL_Event structure.
+ * Values of this type are used to represent keyboard keys, among other places
+ * in the SDL_Keysym::scancode key.keysym.scancode field of the SDL_Event
+ * structure.
  *
- *  The values in this enumeration are based on the USB usage page standard:
- *  https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf
+ * The values in this enumeration are based on the USB usage page standard:
+ * https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf
  */
 typedef enum SDL_Scancode
 {