Add vi support for _config.yml
Translate examples and /index.html (vi)
Fix example; add newline (vi)
Translate 'about' and 'downloads' page (vi)
Small fixes on 'about' and 'downloads' page (vi)
Translate 'libraries' and 'security' pages (vi)
Small fixes on libraries page (vi)
Update security page (vi)
Translate documention section into Vietnamese