[doc] add note/link to full zenstruck/assert expectation API

Author: kbond

README.md

@@ -394,7 +394,8 @@ $browser
 Make assertions about json responses using [JMESPath expressions](https://jmespath.org/)
 See the [JMESPath Tutorials](https://jmespath.org/tutorial.html) to learn more.
 
-**NOTE:** `mtdowling/jmespath.php` is required: `composer require --dev mtdowling/jmespath.php`.
+> **Note**
+> `mtdowling/jmespath.php` is required: `composer require --dev mtdowling/jmespath.php`.
 
 ```php
 /** @var \Zenstruck\Browser\KernelBrowser $browser **/
@@ -437,6 +438,10 @@ $json = $browser
 ;
 ```
 
+> **Note**
+> See the [full `zenstruck/assert` expectation API documentation](https://github.com/zenstruck/assert#expectation-api)
+> to see all the methods available on `Zenstruck\Browser\Json`.
+
 ### PantherBrowser
 
 *The `PantherBrowser` is experimental in 1.0 and may be subject to BC Breaks.*