Document AssertableJson's whereType and whereAllType

http-tests.md

@@ -391,6 +391,25 @@ However, instead of making two separate calls to the `has` method to assert agai
                          ->etc()
                  )
         );
+
+<a name="asserting-json-types"></a>
+#### Asserting JSON Types
+
+You may only want to assert that the properties in the JSON response are of a certain type. The `Illuminate\Testing\Fluent\AssertableJson` class provides the `whereType` and `whereAllType` methods for doing just that.
+
+    $response->assertJson(fn (AssertableJson $json) => 
+        $json->whereType('id', 'integer')
+             ->whereAllType(['users.0.name' => 'string', 'meta' => 'array'])
+    );
+
+Instead of asserting just _one_ type, these methods also give you the option to use union types by either seperating the types with a `|` character, or passing an array of types as the second parameter:
+
+    $response->assertJson(fn (AssertableJson $json) =>
+        $json->whereType('name', 'string|null')
+             ->whereType('id', ['string', 'integer'])
+    );
+
+You may assert any of the following types using this method: `string`, `integer`, `double`, `boolean`, `array`, and `null`.
 
 <a name="testing-file-uploads"></a>
 ## Testing File Uploads