Document the unicode autocompletion feature

[joshop]

I never knew about the \alpha + TAB to get α, etc. feature in the CLI before reading an issue that mentioned it, shouldn't this be documented somewhere? It seems nice to have but I can see most people not even discovering that it exists.
Also, this is probably outside the scope of the same issue but are there plans to add a similar feature to the web version?

[sharkdp]

I never knew about the \alpha + TAB to get α, etc. feature in the CLI before reading an issue that mentioned it, shouldn't this be documented somewhere?

Yes, that is a good idea — thank you. The Unicode-input feature is inspired by Julia. It's probably a good idea to either link to the implementation as a reference, or to use that UNICODE_INPUT array to auto-generate the reference documentation.

are there plans to add a similar feature to the web version?

I don't really remember if I tried it shortly and failed (I think so), or if I simply forgot to implement it in the web version. In any case: yes, it would be great to have this in the web version as well.