Default to preload metadata

src/lib/components/VideoPlayer/README.md

@@ -119,6 +119,7 @@ inner `<mux-player />`.
 
 - when not declared, the `disableCookies` prop is true, unless you explicitly
    set the prop to `false` (therefore it generates a `disable-cookies` attribute)
+- `preload` defaults to `metadata`, for an optimal UX experience together with saved bandwidth
 - the video height and width, when available in the `data` props, are used to
    set a default `aspect-ratio: [width] / [height];` for the `<mux-player />`'s
    `style` attribute