add sapper typings

html/index.d.ts

@@ -572,6 +572,10 @@ export interface AnchorHTMLAttributes extends HTMLAttributes<HTMLAnchorElement>
 	"sveltekit:noscroll"?: true | undefined | null;
 	"sveltekit:prefetch"?: true | undefined | null;
 	"sveltekit:reload"?: true | undefined | null;
+
+	// Sapper
+    "sapper:noscroll"?: true | undefined | null;
+    "sapper:prefetch"?: true | undefined | null;
 }
 
 export interface AudioHTMLAttributes extends MediaHTMLAttributes<HTMLAudioElement> {}