Merge pull request #454 from 0xByteLeon/master

fix: Correct the wrong answer to Exercise 11 in Chapter borrowing

solutions/ownership/borrowing.md

@@ -149,6 +149,6 @@ fn main() {
 
     // add one line below to make a compiler error: cannot borrow `s` as mutable more than once at a time
     // you can't use r1 and r2 at the same time
-    r1.push_str("world");
+    println!("{}, {}", r1, r2);
 }
-```
+```