>> I assume that you mean a mapping from
>>
>> https://lilypond.org/doc/unstable/Documentation/...
>>
>> to
>>
>> https://lilypond.org/doc/v2.25/Documentation/...
>>
>> which doesn't exist. Jonas, what do you think about adding this?
>
> We already have
> https://lilypond.org/doc/development/Documentation/learning/index.html
> and http://lilypond.org/doc/latest/Documentation/learning/index.html
> redirecting there. We can add /unstable/ if that feels more natural,
> not sure...
I think it makes sense.
Werner