Promote free TOTP app instead of Google Authenticator

Promote Aegis Authenticator, a FLOSS app available in F-Droid AND Google PlayStore, instead of Google Authenticator.

aleksis/core/locale/ar/LC_MESSAGES/django.po

@@ -1506,7 +1506,7 @@ msgstr ""
 msgid ""
 "\n"
 "        To start using a token generator, please use your\n"
-"        smartphone to scan the QR code below. For example, use Google\n"
+"        smartphone to scan the QR code below. For example, use Aegis\n"
 "        Authenticator. Then, enter the token generated by the app.\n"
 "      "
 msgstr ""