docs: enhance migration guide metadata for v4.x

Author: dohooo

example/website/pages/_meta.json

@@ -6,5 +6,6 @@
   "custom-animations": "Custom Animations",
   "concepts": "How it works?",
   "compare": "Compare",
-  "faq": "FAQ"
+  "faq": "FAQ",
+  "migration-v4": "Migration to v4.x"
 }

example/website/pages/migration-v4.mdx

@@ -1,6 +1,23 @@
 ---
+id: migration-v4
 title: Migration Guide to v4.x
+sidebar_label: Migration to v4.x
 description: Guide for migrating to react-native-reanimated-carousel v4.x
+keywords:
+  - react-native-reanimated-carousel
+  - reanimated-carousel
+  - reanimated carousel
+  - react-native
+  - snap-carousel
+  - react native
+  - snap carousel
+  - ios
+  - android
+  - carousel
+  - snap
+  - reanimated
+image: 
+slug: /migration-v4
 ---
 
 # Migration Guide to v4.x