Minor: unifiedmailbox: Fix user-visible string

agents/unifiedmailboxagent/unifiedmailboxeditor.cpp

@@ -80,7 +80,7 @@ UnifiedMailboxEditor::UnifiedMailboxEditor(UnifiedMailbox *mailbox, const KShare
     , mMailbox(mailbox)
     , mConfig(config)
 {
-    setWindowTitle(i18nc("@title:window", "Add an Unified MailBox"));
+    setWindowTitle(i18nc("@title:window", "Configure Unified Mailbox"));
     setWindowIcon(QIcon::fromTheme(QStringLiteral("kmail")));
     auto l = new QVBoxLayout(this);