Problem

We have many situations where people would find additional information useful for new users at the cost of output blot.

Potential cases

• cargo news see more Cargo.toml keys and their definitions
• cargo add calling out the lib.name (Help new users understand the unintuitive crate name -> Rust namespace mapping for hyphenated names #15887)
• misnamed config (Cargo should warn if "probably misnamed" config.toml is present.  #8631)
• suggest [workspace] when using path dependencies ("Advertise" workspace feature when dependencies are path-specified #7589)
• unused config relative to a --manifest-path (Cargo does not always search for .cargo/config file in project root #2930)
• No locking available (Cargo 1.91.0 doesn't lock the build directory on illumos #16184)

Proposed Solution

Add a non-lint advice. This is meant to be slightly more verbose output of helpful suggestions that the user can turn off for less output, similar to git.

A fundamental difference between a lint and advice is that a lint is focused on the project while advice is focused on the user.

Notes

#9936 would be helpful so we can easily tell people how to disable advice