Translate Copyright text on footer

client/src/__locales/en.js

@@ -12,6 +12,7 @@ export default {
         on: 'ON',
         off: 'OFF',
         // Footer
+        copyright: 'Copyright',
         homepage: 'Homepage',
         report_an_issue: 'Report an issue',
         // Dashboard

client/src/__locales/vi.js

@@ -12,6 +12,7 @@ export default {
         on: 'Đang bật',
         off: 'Đang tắt',
         // Footer
+        copyright: 'Bản quyền',
         homepage: 'Trang chủ',
         report_an_issue: 'Báo lỗi',
         // Dashboard

client/src/components/ui/Footer.js

@@ -21,7 +21,7 @@ class Footer extends Component {
                         <div className="col-12 col-lg-auto mt-3 mt-lg-0 text-center">
                             <div className="row align-items-center justify-content-center">
                                 <div className="col-auto">
-                                    Copyright © {this.getYear()} <a href="https://adguard.com/">AdGuard</a>
+                                    <Trans>copyright</Trans> © {this.getYear()} <a href="https://adguard.com/">AdGuard</a>
                                 </div>
                                 <div className="col-auto">
                                     <select className="form-control" value={i18n.language} onChange={this.changeLanguage}>