[docs] fix redirects from legacy /repl page (#6894)

site/src/routes/repl/index.svelte

@@ -1,13 +1,14 @@
 <script context="module">
-	export function load({ page: { query }}) {
-		const { gist, example, version } = query;
+	export function load({ page: { query } }) {
+		const gist = query.get('gist');
+		const example = query.get('example');
+		const version = query.get('version');
 
 		// redirect to v2 REPL if appropriate
 		if (/^[^>]?[12]/.test(version)) {
-			const q = Object.keys(query).map(key => `${key}=${query[key]}`).join('&');
 			return {
 				status: 302,
-				redirect: `https://v2.svelte.dev/repl?${q}`
+				redirect: `https://v2.svelte.dev/repl?${query}`
 			};
 		}