Fixed the explanation for life time for return values.

src/ch10-03-lifetime-syntax.md

@@ -209,13 +209,13 @@ This code should compile and produce the result we want when we use it with the
 `main` function in Listing 10-19.
 
 The function signature now tells Rust that for some lifetime `'a`, the function
-takes two parameters, both of which are string slices that live at least as
-long as lifetime `'a`. The function signature also tells Rust that the string
-slice returned from the function will live at least as long as lifetime `'a`.
-In practice, it means that the lifetime of the reference returned by the
-`longest` function is the same as the smaller of the lifetimes of the values
-referred to by the function arguments. These relationships are what we want
-Rust to use when analyzing this code.
+takes two parameters, both of which are string slices that live at least as long
+as lifetime `'a`. The function signature also tells Rust that the string slice
+returned from the function will live at most as long as lifetime `'a`. In
+practice, it means that the lifetime of the reference returned by the `longest`
+function is less than or the same as the smaller of the lifetimes of the values
+referred to by the function arguments. These relationships are what we want Rust
+to use when analyzing this code.
 
 Remember, when we specify the lifetime parameters in this function signature,
 we’re not changing the lifetimes of any values passed in or returned. Rather,