Add ability to add a description to the features.

[Jerrody]

Problem

It's very often to understand what the feature of the N crate does and as a rule maintaners neglect to add the description to the feature in documentation. And the user of this crate cannot understand what feature does, for an example:
nalgebra crate has a cuda feature. What does it mean? Do all math computations perform on the GPU?
In reality, when I asked the maintainer in Discord server what it does he said that this is for interop with CUDA.

Proposed Solution

Add additional field to the feature, like:
my_feature = { features = ["dep:serde", "another_feature"], description = "This is does cool magic" }

And add an option to the maintainer if he doesn't want to add any description to the feature:
my_feature = { features = ["dep:serde", "another_feature"], description = false }

And after this rustdoc parses it or Cargo provides additional data to it and as the result we can see at this page description of each feature (just imagine how it can looks like):

Notes

No response

[weihanglo]

Thanks for your proposal.

This seems to be a duplicate of #4956, and there is a kinda tracking issue #10882 for some extensions of feature field. Closing in favour of those. Thank you.

[Jerrody]

Thanks for your proposal.

This seems to be a duplicate of #4956, and there is a kinda tracking issue #10882 for some extensions of feature field. Closing in favour of those. Thank you.

Alright.