docs: add German language on changing lua-timeago languages

[Nitestack]

I wanted this plugin to support the German language. As to the translations, it's not the most optimal, but a good enough one. A really good one would look like this

return {
    justnow = "Gerade eben",
    minute = { singular = "Vor einer Minute", plural = "Vor {} Minuten" },
    hour = { singular = "Vor einer Stunde", plural = "Vor {} Stunden" },
    day = { singular = "Vor einem Tag", plural = "Vor {} Tagen" },
    week = { singular = "Vor einer Woche", plural = "Vor {} Wochen" },
    month = { singular = "Vor einem Monat", plural = "Vor {} Monaten" },
    year = { singular = "Vor einem Jahr", plural = "Vor {} Jahren" },
}

but since this plugin doesn't support it, I adjusted the translations so it works with the plugin. I think the translation is still pretty good.

[f-person]

Awesome, thanks! Could you please add the language to https://github.com/f-person/lua-timeago instead? Then I'll update the version of lua-timeago that the plugin has :)

[f-person]

I'll need to update the plugin to support this format, though :D

[Nitestack]

I'll need to update the plugin to support this format, though :D

The PR includes a version without templating. The templating was just in case you implement it in the future