Added a gedit code block for step 3.2.3

3-Add-simulated-motors.md

@@ -105,6 +105,10 @@ index 909c067..3d17e23 100644
 
 #### 3.2.3 Edit st.cmd.Linux:
 
+```
+$ gedit st.cmd.Linux &
+```
+
 Make the following change:
 * source iocsh/motors.iocsh