fix: clarify the file name to be used (#1170)
As I was following the steps in this page - https://docs.npmjs.com/creating-node-js-modules, I noticed the following error when using the published package in the test-directory: `Error: Cannot find module 'D:\Learning\npm-docs\use-hello\node_modules\@andrewnessindev\hello\index.js'. Please verify that the package.json has a valid "main" entry` It turned out that I missed providing the main entry even though this [page already mentions to provide it](https://github.com/npm/documentation/blob/2e10e4ed46f0f58adf4c165e8ef21599bc3b325f/content/packages-and-modules/contributing-packages-to-the-registry/creating-node-js-modules.mdx?plain=1#L20). However, it might be more helpful if the docs clarify which file is referred to when[ it says, "In the file"](https://github.com/npm/documentation/blob/2e10e4ed46f0f58adf4c165e8ef21599bc3b325f/content/packages-and-modules/contributing-packages-to-the-registry/creating-node-js-modules.mdx?plain=1#L28). This is my first commit! I followed the instruction it the `contributing.md` file for the commit message. I did not see a requirement to raise an issue first! Please do let me know if I have to raise an issue first or if I have missed anything else. --------- Co-authored-by: Gar <wraithgar@github.com>