Update server.mdx (modelcontextprotocol#149)

Cleaner and more direct since it uses the system's chmod command directly rather than going through Node.js.

Author: charl-kruger

quickstart/server.mdx

@@ -386,7 +386,7 @@ Update your package.json to add type: "module" and a build script:
     "weather": "./build/index.js"
   },
   "scripts": {
-    "build": "tsc && node -e \"require('fs').chmodSync('build/index.js', '755')\"",
+    "build": "tsc && chmod 755 build/index.js",
   },
   "files": [
     "build"