[Feature Request] Custom Translation on Assets and Text

[Roger-luo]

There are some text in English generated by rendering, it would nice if we could change these text to customized version. e.g

Documenter.jl/src/Writers/HTMLWriter.jl

Line 592 in 28de68c

direction = span[".direction"]("Next")

And also it would nice to allow have custom html lang tag, e.g zh-cn

FYI:
JuliaCN/JuliaZH.jl#49

We are using a overwritten version of the above functions as a workaround in JuliaZH currently.

[mortenpi]

We could definitely support this, I would be happy to review a PR for this. Passing a custom dictionary to HTML() is probably the way to go. Or perhaps there is some better approach to i18n library code?

[odow]

Closing in favor of #297.