added italian translation

try bootstrapping approach
updated composer.json

composer.json

@@ -55,7 +55,8 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.0.x-dev"
-        }
+            "dev-master": "2.0.x-dev"
+        },
+        "bootstrap": "yii\\bootstrap5\\i18n\\TranslationBootstrap"
     }
 }

src/i18n/TranslationBootstrap.php

@@ -0,0 +1,27 @@
+<?php
+/**
+ * @package yii2-bootstrap5
+ * @author Simon Karlen <simi.albi@gmail.com>
+ */
+
+namespace yii\bootstrap5\i18n;
+
+use yii\base\Application;
+
+/**
+ * This bootstrap implementation is used to add translations automatically to app configuration
+ */
+class TranslationBootstrap implements \yii\base\BootstrapInterface
+{
+    /**
+     * {@inheritDoc}
+     */
+    public function bootstrap($app)
+    {
+        $app->i18n->translations['yii/bootstrap5*'] = [
+            'class' => '\yii\i18n\GettextMessageSource',
+            'sourceLanguage' => 'en-US',
+            'basePath' => '@yii/bootstrap5/messages'
+        ];
+    }
+}

src/messages/it/messages.po

@@ -12,21 +12,21 @@ msgstr ""
 
 msgctxt "yii/bootstrap5"
 msgid "Button"
-msgstr ""
+msgstr "Bottone"
 
 msgctxt "yii/bootstrap5"
 msgid "Close"
-msgstr ""
+msgstr "Chiudi"
 
 msgctxt "yii/bootstrap5"
 msgid "Home"
-msgstr ""
+msgstr "Partenza"
 
 msgctxt "yii/bootstrap5"
 msgid "Show"
-msgstr ""
+msgstr "Indicare"
 
 msgctxt "yii/bootstrap5"
 msgid "Toggle Dropdown"
-msgstr ""
+msgstr "Attiva/Disattiva lista a tendina"