doc: fix links in README

thermion_dart/README.md

@@ -3,7 +3,7 @@
 <p align="center">
   <a href="https://thermion.dev/quickstart">Quickstart (Flutter)</a> •
   <a href="https://thermion.dev/quickstart">Documentation</a> •
-  <a href="https://thermion.dev/examples">Showcase</a> •
+  <a href="https://thermion.dev/showcase">Showcase</a> •
   <a href="https://dartpad.thermion.dev/">Playground</a> •
   <a href="https://discord.gg/h2VdDK3EAQ">Discord</a>
 </p>