Changes:
````
Rustup to rust-lang#69674
Use visit_place
Check for mutation
Only fires on temporaries
Extend `redundant_clone` to the case that cloned value is not consumed
add CR feedback
Improve documentation
Use `edition:2018` flag more widely
Update tests/ui/needless_doc_main.rs
Move links to the end of each chapter on adding_lints
Move links to the end of each chapter on CONTRIBUTING
Clean-up adding_lints.md
Clean-up CONTRIBUTING.md
needless_doc_main: only check rust code
Use `node_type_opt` over `node_type`
Fix doc
Fix ICE with trivial_bounds feature
clippy_lints: readme: don't mention crates.io since it is no longer used to publish clippy.
update rust-lang.github.io to rustc-dev-guide.rust-lang.org
Improve placeholder in map_unit_fn
Fix match single binding when in a let stmt
Improve error messages for {option,result}_map_unit_fn
Mention the setup instructions in CONTRIBUTING
redundant_pattern: take binding (ref, ref mut) into account in suggestion.
check_pat: delay creation of the "normal" vec until we reach the branch where is is actually needed
deps: bump itertools 0.8 -> 0.9
add lint on File::read_to_string and File::read_to_end
transition rustc-guide to rustc-dev-guide
Rename macro_use_import -> macro_use_imports
warn on macro_use attr
Fix deploy script for tag deploys
````

Fixes rust-lang#69957