Fix an error where rescript -w does not work

Author: jihchi

package.json

@@ -31,7 +31,7 @@
   },
   "scripts": {
     "build": "npm run build:res && snowpack build",
-    "build:res": "rescript",
+    "build:res": "rescript build",
     "clean": "npm run clean:res",
     "clean:res": "rescript clean",
     "start": "snowpack dev",