doc: Sync with README

chrysn · chrysn · commit 52257ab3ab93 · 2022-06-01T09:14:01.000+02:00
This was missed in c17ee0b.
diff --git a/src/lib.rs b/src/lib.rs
@@ -61,6 +61,9 @@
 //!
 //! [C2Rust]: https://c2rust.com/
 //!
+//! Usually, the `c2rust` binary is selected through the `PATH` environment variable.
+//! The `C2RUST` environment variable can be used to override this.
+//!
 //! ---
 //!
 //! The types and constants of RIOT are translated in two forms:
