Dates : only in english?

@spf13 if you guys would like to merge my “multilingual” tutorial PR to the docs, a good place for this piece to go might be inside that, since the topic fits.

@nicolinuxfr in the end, was it the {{ index $mymonths (printf "%d" .Date.Month) }} that @bep suggested that worked? I’d like to try it on my end today.