Update lib.rs - wrong units

[ghost]

1/1000 of a microsecond (us) is nanosecond (ns), not picosecond (ps)

[stappersg]

Sorry for close, the "1/1000 of a microsecond (us) is nanosecond (ns), not picosecond (ps)" remark does deserve further attention.

[stappersg]

Now the open I intented earlier.

[stappersg]

Current version of delay_us():

///delay for N microseconds
/// # Arguments
/// * 'us' - an u64, number of microseconds to busy-wait
#[inline(always)]
pub fn delay_us(us: u64) {
    let us_in_loop = (avr_config::CPU_FREQUENCY_HZ / 1000000 / 4) as u64;
    let loops = us * us_in_loop;
    delay(loops);
}

So it is okay that this merge request is closed.