message: Command toyc should be toyc-ch2 in this chapter
  Closes
diff: @@ -185,9 +185,9 @@ func @main() loc("test/codegen.toy":6:1) {
  }
  ```
  -You can build `toyc` and try yourself: `toyc test/codegen.toy -emit=mlir
  --mlir-print-debuginfo`. We can also check our RoundTrip: `toyc test/codegen.toy
  --emit=mlir -mlir-print-debuginfo > codegen.mlir` followed by `toyc codegen.mlir
  +You can build `toyc-ch2` and try yourself: `toyc-ch2 test/codegen.toy -emit=mlir
  +-mlir-print-debuginfo`. We can also check our RoundTrip: `toyc-ch2 test/codegen.toy
  +-emit=mlir -mlir-print-debuginfo > codegen.mlir` followed by `toyc-ch2 codegen.mlir
  -emit=mlir`.
  Notice how these MLIR operations are prefixed with `toy.` ; by convention we use
  