Update making-changes-to-charm.rst

web/support/kb/juju/making-changes-to-charm.rst

@@ -72,9 +72,11 @@ To execute the tests (based on tox) we still need to download the packages pip a
    sudo apt-get install python-pip
    pip install tox
    
-   sudo pip install tox # This is to allow running "sudo make test"
+   sudo pip install tox
 
 
+N.B. The latter command "sudo pip install tox" is needed in order to run the command "make test" with sudo, 
+because it needs root privileges.
 
 
 At each development cycle