Update the UI to check for 4 characters to match the server

fixes PLT-692

web/react/components/team_signup_display_name_page.jsx

@@ -25,8 +25,8 @@ export default class TeamSignupDisplayNamePage extends React.Component {
         if (!displayName) {
             this.setState({nameError: 'This field is required'});
             return;
-        } else if (displayName.length <= 2 || displayName.length > 15) {
-            this.setState({nameError: 'Name must be 3 or more characters up to a maximum of 15'});
+        } else if (displayName.length < 4 || displayName.length > 15) {
+            this.setState({nameError: 'Name must be 4 or more characters up to a maximum of 15'});
             return;
         }
 

web/react/components/team_signup_url_page.jsx

@@ -35,8 +35,8 @@ export default class TeamSignupUrlPage extends React.Component {
         if (cleanedName !== name || !urlRegex.test(name)) {
             this.setState({nameError: "Use only lower case letters, numbers and dashes. Must start with a letter and can't end in a dash."});
             return;
-        } else if (cleanedName.length <= 2 || cleanedName.length > 15) {
-            this.setState({nameError: 'Name must be 3 or more characters up to a maximum of 15'});
+        } else if (cleanedName.length < 4 || cleanedName.length > 15) {
+            this.setState({nameError: 'Name must be 4 or more characters up to a maximum of 15'});
             return;
         }