fix issue https://github.com/tracim/tracim/issues/720

frontend_lib/src/component/CardPopup/CardPopupCreateContent.jsx

           <input
             type='text'
             className='createcontent__form__input'
+            placeHolder='Nommez votre contenu...'
             value={props.contentName}
             onChange={props.onChangeContentName}
           />