Add an intro paragraph to README and a link to sign up for Slack.
Add an intro paragraph to README and a link to sign up for Slack.

rangle/batarangle,winkerVSbecks/batarangle,bertrandk/batarangle,bertrandk/batarangle,rangle/augury,rangle/augury,winkerVSbecks/batarangle,rangle/batarangle,rangle/augury,rangle/batarangle,clbond/augury,clbond/augury,vanessayuenn/batarangle,winkerVSbecks/batarangle,vanessayuenn/batarangle,bertrandk/batarangle,kushwahashiv/batarangle,kushwahashiv/batarangle,clbond/augury,winkerVSbecks/batarangle,kushwahashiv/batarangle,rangle/augury,rangle/batarangle,vanessayuenn/batarangle,kushwahashiv/batarangle,clbond/augury,vanessayuenn/batarangle