Change adminer headline size

adminer/content.md

@@ -30,7 +30,7 @@ Then point your web server to port 9000 of the container.
 
 Note: This exposes the FastCGI socket to the Internet. Make sure to add proper firewall rules or use a private Docker network instead to prevent a direct access.
 
-## %%STACK%%
+### %%STACK%%
 
 Run `docker stack deploy -c stack.yml %%REPO%%` (or `docker-compose -f stack.yml up`), wait for it to initialize completely, and visit `http://swarm-ip:8080`, `http://localhost:8080`, or `http://host-ip:8080` (as appropriate).