Removing unused import from read_to_string example

Author: haydonryan

library/std/src/fs.rs

@@ -283,7 +283,6 @@ pub fn read<P: AsRef<Path>>(path: P) -> io::Result<Vec<u8>> {
 ///
 /// ```no_run
 /// use std::fs;
-/// use std::error::Error;
 ///
 /// fn main() -> Result<(), Box<dyn Error>> {
 ///     let address: String = fs::read_to_string("address.txt")?;