Clarify to format code with nightly toolchain

README.md

@@ -156,6 +156,26 @@ Persevere is licensed under the Apache License, Version 2.0, (see [LICENSE](LICE
 
 Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Persevere by you, as defined in the Apache-2.0 license, shall be licensed under the Apache License, Version 2.0, without any additional terms or conditions.
 
+We require code submitted to be formatted with Rust's default rustfmt formatter (CI will automatically verified if your code is formatted correctly).
+We are using unstable rustfmt formatting rules, which requires running the formatter with a nightly toolchain, which you can do as follows:
+
+```sh
+$ rustup toolchain install nightly
+$ cargo +nightly fmt
+```
+
+(Building and running Persevere itself can and should happen with the stable toolchain.)
+
+Additionally we are also checking whether there are any clippy warnings in your code.
+You can run clippy locally with:
+
+```sh
+$ cargo clippy --workspace --lib --bins --tests --all-targets -- -Dwarnings
+```
+
+There can be occasions where newer versions of clippy warn about code you haven't touched.
+In such cases we'll try to get those warnings resolved before merging your changes, or work together with you to get them resolved in your merge request.
+
 ## Affiliation
 
 This project has no official affiliation with Amazon Web Services, Inc., Amazon.com, Inc., or any of its affiliates.

src/main.rs

@@ -134,7 +134,7 @@ impl State {
 ///
 /// Source: <https://github.com/takkt-ag/persevere>
 #[derive(Debug, Parser)]
-#[command(version)]
+#[command(version, max_term_width = 100)]
 enum Cli {
     /// Upload a file to S3.
     ///