explicitly label email & phone add sections; fixes https://github.com/vector-im/riot-web/issues/3531

src/components/structures/UserSettings.js

@@ -855,6 +855,7 @@ module.exports = React.createClass({
             addEmailSection = (
                 <div className="mx_UserSettings_profileTableRow" key="_newEmail">
                     <div className="mx_UserSettings_profileLabelCell">
+                        <label>Email</label>
                     </div>
                     <div className="mx_UserSettings_profileInputCell">
                         <EditableText

src/components/views/settings/AddPhoneNumber.js

@@ -147,6 +147,7 @@ export default WithMatrixClient(React.createClass({
         return (
             <form className="mx_UserSettings_profileTableRow" onSubmit={this._onAddMsisdnSubmit}>
                 <div className="mx_UserSettings_profileLabelCell">
+                    <label>Phone</label>
                 </div>
                 <div className="mx_UserSettings_profileInputCell">
                     <div className="mx_UserSettings_phoneSection">