Add slug frontmatter to tutorial pages

Tutorial filenames use numeric prefixes (01-first-steps.md, etc.)
that Docusaurus strips from URLs and vercel.json redirects away via

  /docs/tutorial/:number(\d+)-:path → /docs/tutorial/:path

Without explicit slug frontmatter, docusaurus-plugin-llms wrote
/docs/tutorial/01-first-steps.md etc. — URLs that production
Vercel would 308-redirect to /docs/tutorial/first-steps.md, a path
that didn't exist on disk (404).

Setting slug: to the post-strip name on each tutorial page aligns
the plugin's .md output with the canonical URL, so every link in
llms.txt resolves cleanly.

Author: Aliserag

docs/tutorial/01-first-steps.md

@@ -1,4 +1,5 @@
 ---
+slug: first-steps
 archived: false
 draft: false
 title: First Steps

docs/tutorial/02-hello-world.md

@@ -1,4 +1,5 @@
 ---
+slug: hello-world
 archived: false
 draft: false
 title: Hello World

docs/tutorial/03-resources.md

@@ -1,4 +1,5 @@
 ---
+slug: resources
 archived: false
 draft: false
 title: Resources and the Move (<-) Operator

docs/tutorial/04-capabilities.md

@@ -1,4 +1,5 @@
 ---
+slug: capabilities
 title: Capabilities and Entitlements
 description: An introduction to capabilities, entitlements, and how they interact with resources in Cadence
 meta:

docs/tutorial/05-non-fungible-tokens-1.md

@@ -1,4 +1,5 @@
 ---
+slug: non-fungible-tokens-1
 archived: false
 draft: false
 title: Basic NFT

docs/tutorial/05-non-fungible-tokens-2.md

@@ -1,4 +1,5 @@
 ---
+slug: non-fungible-tokens-2
 archived: false
 draft: false
 title: Intermediate NFTs

docs/tutorial/06-fungible-tokens.md

@@ -1,4 +1,5 @@
 ---
+slug: fungible-tokens
 archived: false
 draft: false
 title: Fungible Tokens

docs/tutorial/07-marketplace-setup.md

@@ -1,4 +1,5 @@
 ---
+slug: marketplace-setup
 title: Marketplace Setup
 ---
 

docs/tutorial/08-marketplace-compose.md

@@ -1,4 +1,5 @@
 ---
+slug: marketplace-compose
 title: Marketplace
 archived: false
 draft: false

docs/tutorial/09-voting.md

@@ -1,4 +1,5 @@
 ---
+slug: voting
 title: Voting Contract
 ---