Fix build errors in FS examples

ctru-rs/src/services/fs.rs

@@ -123,6 +123,9 @@ pub struct Archive {
 /// Create a new file and write bytes to it:
 ///
 /// ```no_run
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// #
 /// use std::io::prelude::*;
 /// use ctru::services::fs::{Fs, File};
 ///
@@ -131,11 +134,17 @@ pub struct Archive {
 ///
 /// let mut file = File::create(&sdmc, "/foo.txt")?;
 /// file.write_all(b"Hello, world!")?;
+/// #
+/// # Ok(())
+/// # }
 /// ```
 ///
 /// Read the contents of a file into a `String`::
 ///
 /// ```no_run
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// #
 /// use std::io::prelude::*;
 /// use ctru::services::fs::{Fs, File};
 ///
@@ -146,12 +155,18 @@ pub struct Archive {
 /// let mut contents = String::new();
 /// file.read_to_string(&mut contents)?;
 /// assert_eq!(contents, "Hello, world!");
+/// #
+/// # Ok(())
+/// # }
 /// ```
 ///
 /// It can be more efficient to read the contents of a file with a buffered
 /// `Read`er. This can be accomplished with `BufReader<R>`:
 ///
 /// ```no_run
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// #
 /// use std::io::BufReader;
 /// use std::io::prelude::*;
 /// use ctru::services::fs::{Fs, File};
@@ -164,6 +179,9 @@ pub struct Archive {
 /// let mut contents = String::new();
 /// buf_reader.read_to_string(&mut contents)?;
 /// assert_eq!(contents, "Hello, world!");
+/// #
+/// # Ok(())
+/// # }
 /// ```
 pub struct File {
     handle: u32,