working on various components of the documentation

docs/blazor/auth.md

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+# Auth Service
+The `IAuthService` provides some useful methods to handle user authentication (login/register).
+
+## Usage
+Simply define the `IAuthService` as a dependency
+
+```csharp
+public interface IAuthService {
+    Task Register(UserRegister register);
+    Task<bool> Login(UserLogin login);
+    Task Logout();
+
+    Task<Token> RefreshLogin();
+    Task<bool> IsLoggedIn();
+}
+```
+## Automatically refresh user sessions
+1. Make sure you have implementented the `AuthMiddleware` how it's described in step 5 of the [installation](./installation.md).
+
+2. After that, the access token of the user gets automatically refreshed as long as the refresh token is valid.