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_metal.h

@@ -37,9 +37,9 @@ extern "C" {
 #endif
 
 /**
- *  \brief A handle to a CAMetalLayer-backed NSView (macOS) or UIView (iOS/tvOS).
+ * A handle to a CAMetalLayer-backed NSView (macOS) or UIView (iOS/tvOS).
  *
- *  \note This can be cast directly to an NSView or UIView.
+ * This can be cast directly to an NSView or UIView.
  */
 typedef void *SDL_MetalView;