This line is a little hidden and needs a bit more description, I think. What about something like:

`First, you must add the domain of your app to the `ALLOWED_DOMAINS` environment variable in the `.env` file in this repo. For example, if were integrating SSO into two apps running at `http://localhost:8888` and `http://localhost:7777`, you would need to include the following in the `.env` of `login.webmaker.org`:

`ALLOWED_DOMAINS="http://localhost:8888 http://localhost:7777"`

Also note typo on environment