shellcheck xmonad_reset_pipe.sh issues

[Sergio Arroutbi]

shellcheck reporting issues:

In xmonad_reset_pipe.sh line 15:
  xmonad_max_pipe=$(ls -1 /proc/"${xmonad_pid}"/fd/ | sort -n | tail -1)
                    ^-----------------------------^ SC2012 (info): Use find instead of ls to better handle non-alphanumeric filenames.


In xmonad_reset_pipe.sh line 16:
  xmobar_max_pipe=$(ls -1 /proc/"${xmobar_pid}"/fd/ | sort -n | tail -1)
                    ^-----------------------------^ SC2012 (info): Use find instead of ls to better handle non-alphanumeric filenames.

For more information:
  https://www.shellcheck.net/wiki/SC2012 -- Use find instead of ls to better ...