docs(oidc): add genric oidc doc

pages/configuration/oauth.mdx

@@ -0,0 +1,89 @@
+---
+title: OIDC Configuration
+description: How to configure OIDC
+---
+
+import { Steps, Callout } from "nextra/components";
+
+<Callout type="warning">
+  **Warning:** With the actual implementation of the OIDC provider, GitHub login
+  provider will be disabled.
+</Callout>
+
+If you want to use OAuth/OIDC, please follow the instructions below.
+
+We will use [Authentik](https://goauthentik.io/) as an OIDC provider example, with base URL `https://authentik.example.com`
+
+<Steps>
+
+### Create an Application/Provider on the Authentik side
+
+You will find the following important information:
+
+- `client_id` => `randomclientid`
+
+- `client_secret` => `randomclientsecret`
+
+- `auth_url` => `https://authentik.example.com/application/o/authorize/`
+
+- `token_url` => `https://authentik.example.com/application/o/token/`
+
+- `userinfo_url`=> `https://authentik.example.com/application/o/userinfo/`
+
+**Note**: the same information needs to be configured on other OIDC providers such as Keycloak, Dex, etc.
+
+### `POSTIZ_GENERIC_OAUTH`
+
+eg: `POSTIZ_GENERIC_OAUTH="true"`
+
+Set to `true` to enable OIDC login.
+
+### `NEXT_PUBLIC_POSTIZ_OAUTH_DISPLAY_NAME`
+
+eg: `Authentik`
+
+Will display the name of the OIDC provider on the login page.
+
+### `NEXT_PUBLIC_POSTIZ_OAUTH_LOGO_URL`
+
+eg: `https://raw.githubusercontent.com/walkxcode/dashboard-icons/master/png/authentik.png`
+
+Will display the logo of the OIDC provider on the login page button.
+
+### `POSTIZ_OAUTH_URL`
+
+eg: `https://authentik.example.com`
+
+The base URL of the OIDC provider.
+
+### `POSTIZ_OAUTH_AUTH_URL`
+
+eg: `https://authentik.example.com/application/o/authorize/`
+
+The authorization URL of the OIDC provider.
+
+### `POSTIZ_OAUTH_TOKEN_URL`
+
+eg: `https://authentik.example.com/application/o/token/`
+
+The token URL of the OIDC provider.
+
+### `POSTIZ_OAUTH_USERINFO_URL`
+
+eg: `https://authentik.example.com/application/o/userinfo/`
+
+The userinfo URL of the OIDC provider.
+
+### `POSTIZ_OAUTH_CLIENT_ID`
+
+eg: `randomclientid`
+
+The client ID of the OIDC provider.
+
+### `POSTIZ_OAUTH_CLIENT_SECRET`
+
+eg: `randomclientsecret`
+
+The client secret of the OIDC provider.
+
+</Steps>