docs(README): promote set -x over set -v for troubleshooting

Author: scop

README.md

@@ -73,10 +73,10 @@ fi
 
 If you find that a given function is producing errors or does not work
 as it should under certain circumstances when you attempt completion,
-try running `set -v` or `set -x` prior to attempting the completion
+try running `set -x` or `set -v` prior to attempting the completion
 again. This will produce useful debugging output that will aid us in
 fixing the problem if you are unable to do so yourself. Turn off the
-trace output by running either `set +v` or `set +x`.
+trace output by running either `set +x` or `set +v`.
 
 To debug dynamic loading of a completion, tracing needs to be turned
 on before the debugged completion is attempted the first time. The