Example and specifications do not match in cargo documentation

[jthulhu]

In the paragraph description of the cargo pkgid subcommand documentation, in the table that specifies the allowed formats, there is a mismatch between the format url#name:version and its example, https://github.com/rust-lang/cargo#crates-io@0.21.0: the format requires a : to separate the name from the version, but the example uses @ (which is consistent with the rest of the specification).

[epage]

Both are actually supported but we have shifted the focus to @ and it looks like that only got partially updated