doc: fix composition doc (useless, obsolete Retry)

CHANGELOG.md

@@ -12,3 +12,8 @@
 
 - Set an error `name` on errors being thrown.  <br/>
   [@ikhoon](https://github.com/ikhoon) in [#530](https://github.com/apollographql/apollo-link/pull/530)
+
+### Docs
+
+- Replace deprecated `Retry` link references with `RetryLink`.  <br/>
+  [@fredericgermain](https://github.com/fredericgermain) in [#555](https://github.com/apollographql/apollo-link/pull/555)

docs/source/composition.md

@@ -14,12 +14,12 @@ Apollo Link ships with two ways to compose links. The first is a method called `
 
 ```js
 import { ApolloLink } from 'apollo-link';
-import Retry from 'apollo-link-retry';
+import { RetryLink } from 'apollo-link-retry';
 import HttpLink from 'apollo-link-http';
 import MyAuthLink from '../auth';
 
 const link = ApolloLink.from([
-  new Retry(),
+  new RetryLink(),
   new MyAuthLink(),
   new HttpLink({ uri: '/graphql' })
 ]);