fix: don't mention outdated Data Transformers (#1675)

Author: chalasr

core/extending.md

@@ -15,9 +15,9 @@ The following tables summarizes which extension point to use depending on what y
 | [State Processors](state-processors)                                                           | custom business logic and computations to trigger before or after persistence (ex: mail, call to an external API...)                                                                                                                |
 | [Normalizers](serialization.md#decorating-a-serializer-and-adding-extra-data)                  | customize the resource sent to the client (add fields in JSON documents, encode codes, dates...)                                                                                                                                    |
 | [Filters](filters.md)                                                                          | create filters for collections and automatically document them (OpenAPI, GraphQL, Hydra)                                                                                                                                            |
-| [Serializer Context Builders](serialization.md#changing-the-serialization-context-dynamically) | Changing the Serialization context (e.g. groups) dynamically                                                                                                                                                                        |
+| [Serializer Context Builders](serialization.md#changing-the-serialization-context-dynamically) | change the Serialization context (e.g. groups) dynamically                                                                                                                                                                        |
 | [Messenger Handlers](messenger.md)                                                             | create 100% custom, RPC, async, service-oriented endpoints (should be used in place of custom controllers because the messenger integration is compatible with both REST and GraphQL, while custom controllers only work with REST) |
-| [DTOs and Data Transformers](dto.md)                                                           | use a specific class to represent the input or output data structure related to an operation                                                                                                                                        |
+| [DTOs](dto.md)                                                           | use a specific class to represent the input or output data structure related to an operation                                                                                                                                        |
 | [Kernel Events](events.md)                                                                     | customize the HTTP request or response (REST only, other extension points must be preferred when possible)                                                                                                                          |
 
 ## Doctrine Specific Extension Points