Say "IR" instead of "IL".

While the specifics of these terms are debatable, "IR" generally
isn't incorrect in this context, and is the more widely recognized
term at this time.

See also the discussion in #267.

Fixes #267.

cranelift/src/wasm.rs

@@ -1,6 +1,6 @@
 //! CLI tool to use the functions provided by the [cretonne-wasm](../cton_wasm/index.html) crate.
 //!
-//! Reads Wasm binary files, translates the functions' code to Cretonne IL.
+//! Reads Wasm binary files, translates the functions' code to Cretonne IR.
 #![cfg_attr(feature = "cargo-clippy", allow(too_many_arguments, cyclomatic_complexity))]
 
 use cton_wasm::{translate_module, DummyEnvironment, ModuleEnvironment};