Copy&pasted examples fail due to auto-added fn main(){}

[eugenesvk]

When trying to follow code examples from Getting Started a user could be enticed by the copy&paste button in Step 2 - Add Benchmark to simply paste the code to his local file, but that sneaky button adds fn main() {, which blocks he invokation of the benchmark macro main function, so the benches would never run

#![allow(unused)]
fn main() {
use criterion::{black_box, criterion_group, criterion_main, Criterion};
use mycrate::fibonacci;

pub fn criterion_benchmark(c: &mut Criterion) {
    c.bench_function("fib 20", |b| b.iter(|| fibonacci(black_box(20))));
}

criterion_group!(benches, criterion_benchmark);
criterion_main!(benches);
}

You should either

• remove the copy&paste button so that users would copy&paste manually without having that blocking main added
• configure docs to generate a button that doesn't copy the hidden text
• Or even better: have self-contained examples that work, then the user would simply download the files and don't have to waste time trying to figure out why the guide doesn't work