rollback dist/vercel.json

package.json

@@ -4,8 +4,7 @@
   "private": true,
   "scripts": {
     "clean": "rm -rf docs/.observablehq/cache",
-    "build": "rm -rf dist && observable build && yarn addvercel",
-    "addvercel": "echo '{\"cleanUrls\": true}' > dist/vercel.json", 
+    "build": "rm -rf dist && observable build", 
     "dev": "observable preview",
     "deploy": "observable deploy",
     "observable": "observable"