docs: add chmod +x instruction before executing scripts

Users should explicitly grant execute permission to downloaded scripts
for transparency and security best practices.

skills/kugetsu/SKILL.md

@@ -201,6 +201,7 @@ To access kugetsu from a remote machine, SSH setup is required.
 Run the SSH setup script inside your container:
 
 ```bash
+chmod +x skills/kugetsu/scripts/sshd-setup.sh
 bash skills/kugetsu/scripts/sshd-setup.sh <username>
 ```