External OAuth provider for Decap CMS. The following environment variables must be set for it to
work:

```shell
OAUTH_CLIENT_ID=(insert_the_client_id)
OAUTH_SECRET=(insert_the_secret)
OAUTH_ORIGINS=www.example.com,oauth.mysite.com
```

Additionaly, when using a host provider other than GitHub, such as Gitlab, the following
environment variables must be set:

```shell
OAUTH_PROVIDER=gitlab
OAUTH_HOSTNAME=https://gitlab.com
OAUTH_TOKEN_PATH=/oauth/token
OAUTH_AUTHORIZE_PATH=/oauth/authorize
OAUTH_SCOPES=api
```

When using GitHub Enterprise, please set `OAUTH_HOSTNAME` to the proper value.

Documentation available on [docs.rs](https://docs.rs/decap_oauth/latest/decap_oauth/).