revert @effect/docgen to preview build URL

Author: bxff

package.json

@@ -40,7 +40,7 @@
     "@changesets/cli": "^2.29.4",
     "@edge-runtime/vm": "^5.0.0",
     "@effect/build-utils": "^0.8.3",
-    "@effect/docgen": "^0.5.2",
+    "@effect/docgen": "https://pkg.pr.new/Effect-TS/docgen/@effect/docgen@fd06738",
     "@effect/eslint-plugin": "^0.3.2",
     "@effect/language-service": "^0.23.3",
     "@effect/vitest": "workspace:^",