fix: Fix heading levels

Signed-off-by: Marcel Klehr <mklehr@gmx.net>

Author: marcelklehr

admin_manual/ai/app_context_agent.rst

@@ -9,7 +9,8 @@ The *context_agent* app is the app that provides AI agent functionality in Nextc
 When the Context Agent app is installed the AI Chat in Nextcloud Assistant will be able to interact with your Nextcloud apps via virtual integrations that are called "tools". They allow the Assistant to perform actions in your Nextcloud upon sending instructions in a chat message.
 Tool groups are only available if their requirements are met. They can be en- and disabled in the AI admin settings.
 
-Currently implemented tools:
+Currently implemented tools
+---------------------------
 
 Artificial intelligence tools
 #############################