Install the dotenv package:
$ npm install dotenv
Create a `.env` file in the root of your project, and add your Webmention.io API key
```bash
WEBMENTION_IO_TOKEN=y0urKeyHeRe
Don't forget to add it to your .gitignore
file. While we are here, let's add the _cache/
folder which will be created when we first fetch webmentions:
_cache/
_site/
node_modules/
.env
How I added dotenv support to Netlify is covered in this Stack Overflow answer.