Merge pull request getify#694 from magul/findIndex-instead-of-find

Fixing note about passing this to findIndex().

es6 & beyond/ch6.md

@@ -368,7 +368,7 @@ points.findIndex( function matcher(point) {
 
 Don't use `findIndex(..) != -1` (the way it's always been done with `indexOf(..)`) to get a boolean from the search, because `some(..)` already yields the `true`/`false` you want. And don't do `a[ a.findIndex(..) ]` to get the matched value, because that's what `find(..)` accomplishes. And finally, use `indexOf(..)` if you need the index of a strict match, or `findIndex(..)` if you need the index of a more customized match.
 
-**Note:** As with other array methods that take callbacks, `find(..)` takes an optional second argument that if set will specify the `this` binding for the callback passed as the first argument. Otherwise, `this` will be `undefined`.
+**Note:** As with other array methods that take callbacks, `findIndex(..)` takes an optional second argument that if set will specify the `this` binding for the callback passed as the first argument. Otherwise, `this` will be `undefined`.
 
 ### `entries()`, `values()`, `keys()` Prototype Methods