fix: show env files in environment variable lessons

Author: AbdullahShafqat-OG

apps/svelte.dev/src/lib/server/content.ts

@@ -13,6 +13,7 @@ const documents = import.meta.glob<string>('./**/*.md', {
 });
 
 const assets = import.meta.glob<string>(['./**/+assets/**', './**/+assets/**/.env'], {
+	exhaustive: true,
 	eager: true,
 	query: '?url',
 	import: 'default',