message: add example for comparing functions over inputs
diff: @@ -43,7 +43,6 @@ Here, we create two benchmark functions which simply call our two Fibonacci impl
  let functions = vec!(fib_slow, fib_fast);
  c.bench_functions("Fibonacci", functions, &20);
  -}
  ```
  Finally, we construct a Vec of the benchmark functions and run the benchmark. This performs two benchmarks ("Fibonacci/Recursive" and "Fibonacci/Iterative") which individually behave the same as other benchmarks seen earlier. In addition to the usual set of plots generated for each individual benchmark, this will generate a set of summary plots at `.criterion/$BENCHMARK/Summary` highlighting the differences between the functions.
  @@ -58,4 +57,13 @@ The [Violin Plot](https://en.wikipedia.org/wiki/Violin_plot) shows the median ti
  ![Line Chart](./user_guide/lines.svg)
  -The line chart shows a comparison of the different functions as the input or input size increases.
  \ No newline at end of file
  +The line chart shows a comparison of the different functions as the input or input size increases, which can be enabled with ParameterizedBenchmark.
  +
  +```rust
  +let parameters = vec![5, 10];
  +let mut benchmark = ParameterizedBenchmark::new("print", |b, i| b.iter(|| print!("{}", i) ), parameters)
  +.with_function("format", |b, i| b.iter(|| format!("{}", i)));
  +
  +c.bench("test_bench_param", benchmark);
  +```
  +
  