Add dox feature

[GuillaumeGomez]

cc @EPashkin

[EPashkin]

Thanks.

[GuillaumeGomez]

I now need to do it for all other crates. Yeay...

[EPashkin]

What not works without defining dox feature in crate?
I tested only build, and it works normally on stable.

[GuillaumeGomez]

This command:

cargo doc --features "dox embed-lgpl-docs" 

[EPashkin]

By rust issue I thought that this feature enabled by cargo doc internally.

[GuillaumeGomez]

I thought as well but it isn't the case. Such disappointment...

[EPashkin]

Even on nightly?

[GuillaumeGomez]

I only tested on nightly.

[EPashkin]

Very strange 😞