Adds documentation for the new environment variable OIDC_PROVIDER_NAME (#32)

Documentation for Drop-OSS/drop#327

Author: Pacodastre

docs/authentication/oidc.md

@@ -6,21 +6,22 @@ OpenID Connect is a OAuth2 extension support by most identity providers.
 
 To configure OIDC, you must set the following environment variables:
 
-| Variable                         | Usage                                                                                               |
-| -------------------------------- | --------------------------------------------------------------------------------------------------- |
-| `OIDC_CLIENT_ID`                 | Client ID from your identity provider.                                                              |
-| `OIDC_CLIENT_SECRET`             | Client secret from your identity provider.                                                          |
-| `OIDC_ADMIN_GROUP`               | Grant admin to users with this group configured in your identity provider. Tested with Authentik.   |
-| `DISABLE_SIMPLE_AUTH` (optional) | Disable simple auth                                                                                 |
-| `OIDC_USERNAME_CLAIM` (optional) | Change the field that Drop pulls the username claim from. Users are merged based on their usernames |
+| Variable                         | Usage                                                                                                       |
+| -------------------------------- | ----------------------------------------------------------------------------------------------------------- |
+| `OIDC_CLIENT_ID`                 | Client ID from your identity provider.                                                                      |
+| `OIDC_CLIENT_SECRET`             | Client secret from your identity provider.                                                                  |
+| `OIDC_ADMIN_GROUP`               | Grant admin to users with this group configured in your identity provider. Tested with Authentik.           |
+| `DISABLE_SIMPLE_AUTH` (optional) | Disable simple auth                                                                                         |
+| `OIDC_USERNAME_CLAIM` (optional) | Change the field that Drop pulls the username claim from. Users are merged based on their usernames         |
+| `OIDC_PROVIDER_NAME` (optional)  | Change the name of the oidc provider that is displayed on the sign-in page. Default is `external provider`. |
 
 And then, you must configure **either**:
 
-#### `OIDC_WELLKNOWN`: A unprotected endpoint that returns a OIDC well-known JSON. Fetched on startup.
+#### `OIDC_WELLKNOWN`: A unprotected endpoint that returns a OIDC well-known JSON. Fetched on startup
 
 ---
 
-#### Individual endpoints:
+#### Individual endpoints
 
 | Variable             | Usage                                                                     |
 | -------------------- | ------------------------------------------------------------------------- |
@@ -29,6 +30,6 @@ And then, you must configure **either**:
 | `OIDC_USERINFO`      | Userinfo endpoint. Usually ends with `userinfo`.                          |
 | `OIDC_SCOPES`        | Comma separated list of scopes. Requires, at least, `openid` and `email`. |
 
-
 ## Redirect URL
-Drop uses the `EXTERNAL_URL` environment variable to create the callback URL: `$EXTERNAL_URL/auth/callback/oidc`. 
+
+Drop uses the `EXTERNAL_URL` environment variable to create the callback URL: `$EXTERNAL_URL/auth/callback/oidc`.