po: Make Team-Website a private field by renaming to X-Team-Website

Warned-by: i18nspector

po/vi.po

@@ -16,9 +16,9 @@ msgstr ""
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
-"Team-Website: <http://translationproject.org/team/vi.html>\n"
 "Plural-Forms: nplurals=1; plural=0;\n"
 "X-Generator: LocFactoryEditor 1.8\n"
+"X-Team-Website: <http://translationproject.org/team/vi.html>\n"
 "X-Poedit-SourceCharset: UTF-8\n"
 "X-Poedit-Basepath: ../\n"