Feature: generate PDF versions for each locale

[CosmoMyzrailGorynych]

Use case: for offline use at schools, subways, for people who prefer working with pdfs (i guess), for print, and as a backup when an internet connection is not stable (it is still the case for 21st century).

This can be achieved relatively easy with one of these modules:

• gulp-markdown-pdf
• electron-pdf as it can use the existing site as a source.
• something along these lines with wkhtmltopdf