Clarify the docstring of lang keyword

[mortenpi]

Using slightly more accurate language, ref: #1223 (comment)

[nil-is-lin]

Thank you very much for your reply. Is there any way to switch different web pages according to the language, which may be useful for some non-native English users. I want to write web pages in two languages together, which may not be a wise way, but it does work. Does this need to declare two kinds of Lang tag?

[mortenpi]

Documenter doesn't have any built-in support for multi-language docs and nothing specific on the roadmap for this (see #297, #658 for some discussion on this).

The lang keyword is a very specific feature to be able to declare the language of the current document, by setting the lang attribute. But it doesn't help you have multiple languages.

[nil-is-lin]

OK, I see. I'll try something else. Thank you