macOS user need to be reminded

[qizidog]

There is no default timeout command in macOS, it is necessary to remind macOS users to install gtimeout and do alias, otherwise bt_list_wrapper.sh will crash.

brew install coreutils
echo "alias timeout=gtimeout" >> ~/.zshrc

What's more, I think it's better to remind that dependencies should be installed by users(not automatically installed with tmux-browser).

Dependencies
Firefox/Chrome/Chromium (Tested on Firefox)
brotab
resurrect
wmctrl (recommended, used to jump to the window)