wrong documentation is shows for println macro

[santhosh-tekuri]

I am using rust-analyzer with vscode.

use async_std::println;

fn main() {
    println!("Hello, world!");
}

actual behavior:
when I hover mouse over println in main function, the documentation tooltip show doc for println from std::macros

expected behaviour:
it should show doc for println from async_std

[Kohei316]

@rustbot claim