Auto merge of #34540 - jupp0r:patch-1, r=steveklabnik

Improve code example for try!

This change improves the code example for try!,
avoiding to use try! in the example code that shows
what code constructs try! can replace.

Author: bors

src/libcore/result.rs

@@ -175,8 +175,11 @@
 //! }
 //!
 //! fn write_info(info: &Info) -> io::Result<()> {
-//!     let mut file = try!(File::create("my_best_friends.txt"));
 //!     // Early return on error
+//!     let mut file = match File::create("my_best_friends.txt") {
+//!            Err(e) => return Err(e),
+//!            Ok(f) => f,
+//!     };
 //!     if let Err(e) = file.write_all(format!("name: {}\n", info.name).as_bytes()) {
 //!         return Err(e)
 //!     }