update changelog for 1.13 socket reference change

CHANGELOG.md

 ## 1.14.0
 
 ### Core library changes
 * `dart:math`
   * `Random` added a `secure` constructor returning a cryptographically secure
     random generator which reads from the entropy source provided by the
     embedder for every generated random value.
 
 ## 1.13.0
 
 ### Core library changes
 * `dart:async`
   * `StreamTransformer` instances created with `fromHandlers` with no
     `handleError` callback now forward stack traces along with errors to the
     resulting streams.
 
 * `dart:core`
   * `Uri` added `removeFragment` method.
   * `String.allMatches` (implementing `Pattern.allMatches`) is now lazy,
     as all `allMatches` implementations are intended to be.
   * `Resource` is deprecated in favor of the resource package.
     See https://pub.dartlang.org/packages/resource to learn more. This is
     the last release to contain the Resource class.
 
 * `dart:io`
   * `HttpClient` no longer sends URI fragments in the request. This is not
     allowed by the HTTP protocol.
     The `HttpServer` still gracefully receives fragments, but discards them
     before delivering the request.
-  * Removed server socket references. The use of server socket references
-    was deprecated back in 1.9. Use the `shared` flag when creating listening
-    sockets and `HttpServer` to distribute accepted sockets between isolates.
+  * To allow connections to be accepted on the same port across different
+    isolates, set the `shared` argument to `true` when creating server socket
+    and `HttpServer` instances.
+    * The deprecated `ServerSocketReference` and `RawServerSocketReference`
+      classes have been removed.
+    * The corresponding `reference` properties on `ServerSocket` and
+      `RawServerSocket` have been removed.
 
 * `dart:isolate`
   * `Isolate` added `packageRoot` and `packageMap` getters.
   * `Isolate.spawnUri` added `packageMap` parameter.
 
 ### Tool changes
 
 * `docgen` and 'dartdocgen' no longer ship in the sdk. The `docgen` sources have
    been removed from the repository.
 
@@ skipping 553 matching lines @@
     they will keep the Dart process alive until they time out. This fixes the
     handling of persistent connections. Previously, the client would shut down
     immediately after a request.
 
   * **Breaking change:** `HttpServer` no longer compresses all traffic by
     default. The new `autoCompress` property can be set to `true` to re-enable
     compression.
 
 * `dart:isolate`: `Isolate.spawnUri` added the optional `packageRoot` argument,
   which controls how it resolves `package:` URIs.