modify the guideline to refer to pre-commit hooks

Author: Radonirinaunimi

CONTRIBUTING.md

@@ -2,10 +2,10 @@
 
 ## Rust
 
-- Before you commit, make sure that your code compiles with `cargo check` and
-  that it has been formatted properly; `cargo fmt` does that for you. Also
-  check if your changes introduce any new linter warnings by running `cargo
-  clippy`
+- Before you commit, make sure that you have [pre-commit](https://pre-commit.com/)
+  installed. This will ensure that the code is formatted correctly and that
+  it compiles properly. Also, check if your changes introduce any new linter
+  warnings by running `cargo clippy`.
 - Make sure to keep `CHANGELOG.md` up-to-date.
 - Make sure not to use Rust features newer than the specified minimum supported
   Rust Version (MSRV), which is documented in the [README](README.md). You can

docs/maintainers-guide.md

@@ -48,6 +48,7 @@
 - `_config.yml`: configuration file for PineAPPL's Github-pages website
 - `install-capi.sh`: POSIX-compliant shell script to download and install
   PineAPPL's pre-built CAPI
+- `.pre-commit-config.yaml`: pre-commit hooks configuration
 
 [cargo-xtask]: https://github.com/matklad/cargo-xtask
 [release page]: https://github.com/NNPDF/pineappl/releases