Added write your own SDK guide

package.json

@@ -19,6 +19,7 @@
     "@orama/orama": "^3.1.18",
     "@typescript/ata": "^0.9.8",
     "@typescript/vfs": "^1.6.4",
+    "beautiful-mermaid": "^1.1.3",
     "class-variance-authority": "^0.7.1",
     "cnfast": "^0.0.8",
     "fumadocs-core": "16.12.1",
@@ -26,7 +27,8 @@
     "fumadocs-twoslash": "^3.3.0",
     "fumadocs-ui": "npm:@fumadocs/[email protected]",
     "lucide-react": "^1.3.0",
-    "next": "^16.2.12",
+    "next": "^16.3.4",
+    "next-themes": "^0.4.6",
     "react": "^19.2.8",
     "react-dom": "^19.2.8",
     "takumi-js": "^2.4.0",