clarify that find returns first match

the example for `find` was misleading in that it fails to mention the result is either `None` or `Some` containing only the first match. Further confusing the issue is the `println!` statement, "We got some numbers!"

Author: David Elliott

src/doc/trpl/iterators.md

@@ -150,15 +150,16 @@ let greater_than_forty_two = (0..100)
                              .find(|x| *x > 42);
 
 match greater_than_forty_two {
-    Some(_) => println!("We got some numbers!"),
-    None => println!("No numbers found :("),
+    Some(_) => println!("Found a match!"),
+    None => println!("No match found :("),
 }
 ```
 
 `find` takes a closure, and works on a reference to each element of an
 iterator. This closure returns `true` if the element is the element we're
-looking for, and `false` otherwise. Because we might not find a matching
-element, `find` returns an `Option` rather than the element itself.
+looking for, and `false` otherwise. `find` returns the first element satisfying
+the specified predicate. Because we might not find a matching element, `find`
+returns an `Option` rather than the element itself.
 
 Another important consumer is `fold`. Here's what it looks like: