add label to tutorial parts (#336)

Author: Rich-Harris

apps/svelte.dev/content/tutorial/01-svelte/index.md

@@ -1,5 +1,6 @@
 ---
 title: Basic Svelte
+label: Part 1
 scope: { 'prefix': '/src/lib/', 'name': 'src' }
 focus: /src/lib/App.svelte
 ---

apps/svelte.dev/content/tutorial/02-advanced-svelte/index.md

@@ -1,5 +1,6 @@
 ---
 title: Advanced Svelte
+label: Part 2
 scope: { 'prefix': '/src/lib/', 'name': 'src' }
 focus: /src/lib/App.svelte
 ---

apps/svelte.dev/content/tutorial/03-sveltekit/index.md

@@ -1,5 +1,6 @@
 ---
 title: Basic SvelteKit
+label: Part 3
 scope: { 'prefix': '/', 'name': 'project' }
 focus: /src/routes/+page.svelte
 ---

apps/svelte.dev/content/tutorial/04-advanced-sveltekit/index.md

@@ -1,5 +1,6 @@
 ---
 title: Advanced SvelteKit
+label: Part 4
 scope: { 'prefix': '/', 'name': 'project' }
 focus: /src/routes/+page.svelte
 ---

apps/svelte.dev/src/routes/tutorial/[...slug]/content.server.ts

@@ -249,7 +249,7 @@ export async function load_exercise(slug: string): Promise<Exercise> {
 		part: {
 			slug: part.slug,
 			title: part.metadata.title,
-			label: 'TODO' // 'Part 1' etc
+			label: part.metadata.label
 		},
 		chapter: {
 			slug: chapter.slug,