use transition-discrete in blog post instead of arbitrary property

Author: RobinMalfait

src/pages/docs/v4-beta.mdx

@@ -1105,7 +1105,7 @@ The new `starting` variant adds support for the new CSS `@starting-style` featur
 ```html
 <div>
   <button popovertarget="my-popover">Check for updates</button>
-  <div popover id="my-popover" class="opacity-0 transition-all duration-500 [transition-behavior:allow-discrete] open:opacity-100 starting:open:opacity-0">
+  <div popover id="my-popover" class="opacity-0 transition-all duration-500 transition-discrete open:opacity-100 starting:open:opacity-0">
     <!-- ... -->
   </div>
 </div>