stabilize revese shell code example

Example 1: upgrade shell tty

python -c 'import pty; pty.spawn("/bin/bash")'

Example 2: upgrade shell tty

# In reverse shell
$ python -c 'import pty; pty.spawn("/bin/bash")'
Ctrl-Z

# In Kali
$ stty raw -echo
$ fg

# In reverse shell
$ reset
$ export SHELL=bash
$ export TERM=xterm-256color
$ stty rows <num> columns <cols>