Fix code-example gen causing clippy warnings on windows (#4897)

And fix broken autogen warning.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/4897/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/4897/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/4897/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG

- [PR Build Summary](https://build.rerun.io/pr/4897)
- [Docs
preview](https://rerun.io/preview/9497fbee4c374f63d8909f3e63d9d15922d8aac3/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/9497fbee4c374f63d8909f3e63d9d15922d8aac3/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

docs/code-examples/build.rs

@@ -42,7 +42,9 @@ fn main() {
                         "let args = _args;",
                     );
                     let contents = format!(
-                        "//! DO NOT EDIT! This is a py. The original is in {path:?}.\n{contents}"
+                        "//! DO NOT EDIT! This file was autogenerated by `{}`. The original is in `{}`.\n{contents}",
+                        file!().replace('\\', "/"),
+                        path.to_str().unwrap().replace('\\', "/"),
                     );
 
                     let target_path = examples_path.join(format!("{example_name}.rs"));