docs: update xAI provider link in v3.12.0 release notes

Author: hannesrudolph

docs/update-notes/v3.12.0.md

@@ -4,7 +4,7 @@ This release introduces xAI provider support, improves diff editing, enhances UI
 
 ## Provider Updates
 
-*   Added xAI provider and exposed reasoning effort options for Grok on OpenRouter. (thanks Cline!)
+*   Added [xAI provider](/providers/xai) and exposed reasoning effort options for Grok on OpenRouter. (thanks Cline!)
 *   Added support for OpenAI `o3` & `4o-mini` models. (thanks PeterDaveHello!)
 
 ## Profile-Specific Diff Settings