docs: add POT file to site example

docs/site-example/i18n/gluon-site.pot

@@ -0,0 +1,11 @@
+msgid ""
+msgstr "Content-Type: text/plain; charset=UTF-8"
+
+msgid "gluon-config-mode:welcome"
+msgstr ""
+
+msgid "gluon-config-mode:pubkey"
+msgstr ""
+
+msgid "gluon-config-mode:reboot"
+msgstr ""