Fix script/bench-rust-deflate typo
//
// Wuffs' C code doesn't depend on Rust per se, but this program gives some
// performance data for specific Rust Deflate implementations. The equivalent
-// Wuffs benchmarks (on the same test images) are run via:
+// Wuffs benchmarks (on the same test files) are run via:
//
// wuffs bench std/deflate
//
