Add crate removal instructions for crates.io.

[smarnach]

As promised in the meeting, I added a hint that we need to create a CloudFront invalidation when removing crates or versions now that rust-lang/crates.io#1871 is merged.

I also added a guess what else needs to be done, in the hope that we clarify the actual steps during the review process. :)

[smarnach]

Related: #63

[carols10cents]

I think this is a good start, so i'm in favor of merging it, but it's not everything... these scripts don't remove crates from the index or from S3, for example. And this would allow someone else to take the crate name and/or version, which is what we want in some cases but not others.

I am ok with getting started with this though, I just have some suggestions for making a bit clearer which parts of the commands are placeholders that need to be filled in.

[smarnach]

@carols10cents Thanks for the review! I was assuming that the binaries also take care of S3 and the index, but I just confirmed they don't. I added bullet points for these steps to the instructions for now (without any details how to do it). However, a better solution would be to improve the binaries to take care of these steps as well. The only step we probably want to do manually is the CloudFront invalidation, since the Heroku app currently doesn't have the permissions to do it.

Could you please take another look?

[pietroalbini]

The only step we probably want to do manually is the CloudFront invalidation, since the Heroku app currently doesn't have the permissions to do it.

I'm totally fine giving Heroku the permissions to invalidate the static.crates.io CloudFront distribution btw.

[pietroalbini]

Also note that the IAM user doesn't have the permissions to delete objects yet.

[smarnach]

I'm totally fine giving Heroku the permissions to invalidate the static.crates.io CloudFront distribution btw.

I was looking at it from the perspective of the code we'd need to write. We don't have any CloudFront client code so far, and I'm not sure I'd want to pull in Rusoto just for this. And the AWS API isn't trivial to use, even for a single invalidation. (S3 provides a REST API which is a lot easier to use.)

We already have the code to delete S3 objects, though.

[smarnach]

@carols10cents Would you mind taking another look? This would help finally moving the doc to rust-forge.

[carols10cents]

LGTM! Sorry for the delay!

[smarnach]

Thanks for merging!

@pietroalbini All PRs against the crate removal doc are now merged, so you can go ahead and move it to rust-forge. Please leave a file with a link in the old location. :)