Update index.md

Author: gwangmu

docs/software/container-engine/index.md

@@ -56,7 +56,7 @@ $ srun --environment=ubuntu --pty bash
 [compute-node]$ 
 ```
 
-??? example "Entering the defined environment"
+??? example "Entering the environment on Daint"
     ```console
     [daint-ln002]$ srun --environment=ubuntu --pty bash   # (1)