Specify whether false-positives are expected in docs

I've run into lints that are false positives on clippy, but I've been unsure if they're expected or not. I think it would be helpful if the lints in the clippy collection (that are expected no false positives) showed something like:

We expected this lint, `lint_name_here` to have no false positives. If you found one, please report it! https://...../issues/false-positive-template

This could be both in the online docs (perhaps a label/button: No false positives. Found One? in the header line of the lint), as well as in the command line output.

Happy to make the changes if people are amenable.

Start by locating the online documentation for lints in the clippy collection and the code responsible for command-line lint output. Check how lint metadata and documentation headers are represented, then define the expected wording and false-positive report link for applicable lints. Done means the notice appears consistently in both the relevant online docs and CLI output.