Update README.md - #27

New AutoCua/utils/errors.py, error_text(e): the message an exception
carries (its args; strerror and filename for OS errors; timeout or exit
status for subprocess errors), built from the exception's fields and
never from str(e) or a traceback. The sixteen JSON replies in the app's
Flask routes, the iOS and Android connectors and the three Telegram views
use it in place of str(e). What the person sees stays the same, minus the
"[Errno N]" prefix. Closes the fourteen open py/stack-trace-exposure
alerts (#5, #8-#15, #27, #30-#32, #35), which treat str(e) of a caught
exception as stack-trace text once it reaches a reply.