Adding to the features.json file

Once you have your folder for the feature, you can add the feature to the settings page in the /features/features.json file. At the top of the array object in the file, add this:

{
    "version": 2,
    "id": "name of the folder that you made for your feature",
    "versionAdded": "the current version"
},

Once you do that, you can open up the settings page and the feature should appear at the top.

info

Scripts and styles are cached when enabled. If you update the userscripts or userstyles in the data.json file while the feature is enabled, make sure to disable and reenable the feature from the settings page to see changes to the feature on the Scratch website.