docs: add outline oidc docs (#3829)

docs/content/en/integration/openid-connect/outline/index.md

@@ -0,0 +1,83 @@
+---
+title: "Outline"
+description: "Integrating Outline with the Authelia OpenID Connect Provider."
+lead: ""
+date: 2022-06-15T17:51:47+10:00
+draft: false
+images: []
+menu:
+  integration:
+    parent: "openid-connect"
+weight: 620
+toc: true
+community: true
+---
+
+## Tested Versions
+
+* [Authelia]
+  * [v4.36.4](https://github.com/authelia/authelia/releases/tag/v4.36.4)
+* [Outline]
+  * 0.65.2
+
+## Before You Begin
+
+You are required to utilize a unique client id and a unique and random client secret for all [OpenID Connect] relying
+parties. You should not use the client secret in this example, you should randomly generate one yourself. You may also
+choose to utilize a different client id, it's completely up to you.
+
+This example makes the following assumptions:
+
+* __Application Root URL:__ `https://outline.example.com`
+* __Authelia Root URL:__ `https://auth.example.com`
+* __Client ID:__ `outline`
+* __Client Secret:__ `outline_client_secret`
+
+## Configuration
+
+### Application
+
+To configure [Outline] to utilize Authelia as an [OpenID Connect] Provider:
+
+1. Configure the following environment options:
+```text
+URL=https://outline.example.com
+FORCE_HTTPS=true
+
+OIDC_CLIENT_ID=outline
+OIDC_CLIENT_SECRET=outline_client_secret
+OIDC_AUTH_URI=https://auth.example.com/api/oidc/authorization
+OIDC_TOKEN_URI=https://auth.example.com/api/oidc/token
+OIDC_USERINFO_URI=https://auth.example.com/api/oidc/userinfo
+OIDC_USERNAME_CLAIM=preferred_username
+OIDC_DISPLAY_NAME=Authelia
+OIDC_SCOPES="openid profile email"
+```
+
+### Authelia
+
+The following YAML configuration is an example __Authelia__
+[client configuration](../../../configuration/identity-providers/open-id-connect.md#clients) for use with [Outline]
+which will operate with the above example:
+
+```yaml
+- id: outline
+  secret: outline_client_secret
+  public: false
+  authorization_policy: two_factor
+  scopes:
+    - openid
+    - profile
+    - email
+  redirect_uris:
+    - https://outline.example.com/auth/oidc.callback
+  userinfo_signing_algorithm: none
+```
+
+## See Also
+
+* [Outline OpenID Connect Documentation](https://app.getoutline.com/share/770a97da-13e5-401e-9f8a-37949c19f97e/doc/oidc-8CPBm6uC0I)
+
+[Authelia]: https://www.authelia.com
+[Outline]: https://www.getoutline.com/
+[OpenID Connect]: ../../openid-connect/introduction.md