Add support for clippy.toml (#835)

* Add support for clippy.toml

* Regenerate documentation

* Fix build file naming

* Fix use of depset

* Fix path for non-root config file locations

* Document Rust 1.34.0 requirement

* Regenerate documentation

* Document location of clippy documentation

* buildifier

* Use modern python formatting

Co-authored-by: UebelAndre <github@uebelandre.com>

* Use modern python formatting

Co-authored-by: UebelAndre <github@uebelandre.com>

* Add a test

* Address review comments

Co-authored-by: UebelAndre <github@uebelandre.com>
diff --git a/docs/rust_clippy.vm b/docs/rust_clippy.vm
index d444a04..abfc478 100644
--- a/docs/rust_clippy.vm
+++ b/docs/rust_clippy.vm
@@ -22,3 +22,11 @@
 This will enable clippy on all [Rust targets](./defs.md).
 
 Note that targets tagged with `noclippy` will not perform clippy checks
+
+To use a local clippy.toml, add the following flag to your `.bazelrc`. Note that due to
+the upstream implementation of clippy, this file must be named either `.clippy.toml` or
+`clippy.toml`. Using a custom config file requires Rust 1.34.0 or newer.
+
+```text
+build --@rules_rust//:clippy.toml=//:clippy.toml
+```