update README

README.md

@@ -332,13 +332,11 @@ As of Swift 5.1, `Attributes` can be accessed via dynamic member keypath lookup
 let favoriteColor: String = person.favoriteColor
 ```
 
-🗒 `Attributes` can also be accessed via the older `subscript` operator as follows:
+:warning:  `Attributes` can also be accessed via the older `subscript` operator, but this is a deprecated feature that will be removed in the next major version:
 ```swift
 let favoriteColor: String = person[\.favoriteColor]
 ```
 
-In both cases you retain type-safety. It is best practice to pick an attribute access syntax and stick with it. At some point in the future the syntax deemed less desirable may be deprecated.
-
 #### `Transformer`
 
 Sometimes you need to use a type that does not encode or decode itself in the way you need to represent it as a serialized JSON object. For example, the Swift `Foundation` type `Date` can encode/decode itself to `Double` out of the box, but you might want to represent dates as ISO 8601 compliant `String`s instead. The Foundation library `JSONDecoder` has a setting to make this adjustment, but for the sake of an example, you could create a `Transformer`.