Refer to already existing example

docs/modules/ROOT/pages/cops_performance.adoc

@@ -1170,9 +1170,8 @@ This cop identifies places where `map { ... }.compact` can be replaced by `filte
 === Safety
 
 This cop's autocorrection is unsafe because `map { ... }.compact` might yield
-different results than `filter_map`. For example, `[true, false, nil].compact`
-gives `[true, false]`, while `[true, false, nil].filter_map(&:itself)` results in
-`[true]`, i.e. `filter_map` also filtered out falsy values.
+different results than `filter_map`. As seen in the example above, `filter_map`
+also filters out falsy values, while `compact` only gets rid of `nil`.
 
 === Examples