update assert_nothing_raised in testing.md

guides/source/testing.md

@@ -287,7 +287,7 @@ specify to make your test failure messages clearer.
 | `assert_not_in_delta( expected, actual, [delta], [msg] )`        | Ensures that the numbers `expected` and `actual` are not within `delta` of each other.|
 | `assert_throws( symbol, [msg] ) { block }`                       | Ensures that the given block throws the symbol.|
 | `assert_raises( exception1, exception2, ... ) { block }`         | Ensures that the given block raises one of the given exceptions.|
-| `assert_nothing_raised( exception1, exception2, ... ) { block }` | Ensures that the given block doesn't raise one of the given exceptions.|
+| `assert_nothing_raised { block }`                                | Ensures that the given block doesn't raise any exceptions.|
 | `assert_instance_of( class, obj, [msg] )`                        | Ensures that `obj` is an instance of `class`.|
 | `assert_not_instance_of( class, obj, [msg] )`                    | Ensures that `obj` is not an instance of `class`.|
 | `assert_kind_of( class, obj, [msg] )`                            | Ensures that `obj` is an instance of `class` or is descending from it.|