Add Team Description to the Team Settings (#4652)

* draft

* Add Team Description to the Team Settings

* add tooltips for team description

* made changes per PM review

* add message when there is no description set in the team

* squash

webapp/components/create_team/components/display_name.jsx

@@ -38,7 +38,7 @@ export default class TeamSignupDisplayNamePage extends React.Component {
             this.setState({nameError: (
                 <FormattedMessage
                     id='create_team.display_name.charLength'
-                    defaultMessage='Name must be {min} or more characters up to a maximum of {max}'
+                    defaultMessage='Name must be {min} or more characters up to a maximum of {max}. You can add a longer team description later.'
                     values={{
                         min: Constants.MIN_TEAMNAME_LENGTH,
                         max: Constants.MAX_TEAMNAME_LENGTH