gui: gradle: added a warning note on the .touistl extension problem
gui: gradle: added a warning note on the .touistl extension problem

[skip ci]

touist/touist,FredMaris/touist,FredMaris/touist,touist/touist,olzd/touist,touist/touist,touist/touist,olzd/touist,FredMaris/touist,olzd/touist