Mention tenancy initialization by request data

docs/source/v2/middleware-configuration.blade.md

@@ -7,6 +7,32 @@ section: content
 
 # Middleware Configuration {#middleware-configuration}
 
+## Header or query parameter based identification {#header-or-query-parameter-based-identification}
+
+To identify tenants using request headers or query parameters, you may use the `InitializeTenancyByRequestData` middleware.
+
+Create a **central** route (don't apply the `tenancy` middleware group on it and don't put it into `routes/tenant.php`) and apply this middleware on the route:
+
+```php
+\Stancl\Tenancy\Middleware\InitializeTenancyByRequestData::class
+```
+
+To customize the header, query parameter, and `onFail` logic, you may do this in your `AppServiceProvider::boot()`:
+
+```php
+// use Stancl\Tenancy\Middleware\InitializeTenancyByRequestData::class;
+
+$this->app->bind(InitializeTenancyByRequestData::class, function ($app) {
+    return new InitializeTenancyByRequestData('header name', 'query parameter', function ($exception) {
+        // return redirect()->route('foo');
+    });
+});
+```
+
+To disable identification using header or query parameter, set the respective parameter to `null`.
+
+## Customizing the onFail logic {#customizing-the-onfail-logic}
+
 When a tenant route is visited and the tenant can't be identified, an exception is thrown. If you want to change this behavior, to a redirect for example, add this to your `app/Providers/AppServiceProvider.php`'s `boot()` method:
 
 ```php
@@ -17,4 +43,4 @@ $this->app->bind(InitializeTenancy::class, function ($app) {
         // return redirect()->route('foo');
     });
 });
-```
+```