feat: add meta.json for Applications documentation

- Introduced a new meta.json file to structure the Applications documentation.
- Included pages for advanced topics, build types, preview deployments, rollbacks, zero downtime, and going production.

apps/docs/content/docs/core/applications/meta.json

@@ -0,0 +1,11 @@
+{
+	"title": "Applications",
+	"pages": [
+		"advanced",
+		"build-type",
+		"preview-deployments",
+		"rollbacks",
+		"zero-downtime",
+		"going-production"
+	]
+}