[backend] Affichage des dimensions idéales pour la photo de couverture

backend/views/producer/update.php

                         echo '<input type="checkbox" name="delete_logo" id="delete_logo" /> <label for="delete_logo">Supprimer le logo</label><br /><br />';
                     }
                     ?>
-                    <?= $form->field($model, 'photo')->fileInput() ?>
+                    <?= $form->field($model, 'photo')->fileInput()->hint('Format idéal : 900 x 150 px') ?>
                     <?php
                     if (strlen($model->photo)) {
                         echo '<img src="'.Yii::$app->urlManagerProducer->getHostInfo().'/'.Yii::$app->urlManagerProducer->baseUrl.'/uploads/' . $model->photo . '" width="400px" /><br />';