Added node version requirement for running the test.

Added "engines" key to package.json.
Updated readme.md to document the requirement.

package.json

@@ -10,6 +10,9 @@
     "type": "git",
     "url": "git+https://github.com/fate-srd/fate-product-list.git"
   },
+  "engines": {
+    "node": "20.x"
+  },
   "author": "amazingrando",
   "license": "ISC",
   "bugs": {

readme.md

@@ -17,7 +17,8 @@ The submission will be reviewed and added to the Fate SRD. This usually happens
 If you are comfortable with editing files and git/Github, you may [create a pull request](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request). It will be reviewed and added to the site.
 
 There is a Github check configured to ensure the CSV file is in the expected order. This check is implemented a small
-Javascript script that runs under [Nodejs](https://nodejs.org/) version 20.x. (The code will probably run under older versions, too.)
+Javascript script that runs under [Nodejs](https://nodejs.org/) version 20.x, which is required. You will get a warning
+from `npm` if you try this with older versions of Nodejs.
 
 To check the CSV file order locally, before you push your changes to Github, you must have a current version of Nodejs 
 installed, then run the following commands.