Update the blog link of discord app in showcase.

Summary:
Fixed the broken blog link for the showcase of discord app.

Verified the new blog link works.

Sign the [CLA][2], if you haven't already.

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Make sure all **tests pass** on both [Travis][3] and [Circle CI][4]. PRs that break tests are unlikely to be merged.

For more info, see the ["Pull Requests"][5] section of our "Contributing" guidelines.

[1]: https://medium.com/martinkonicek/what-is-a-test-plan-8bfc840ec171#.y9lcuqqi9
[2]: https://code.facebook.com/cla
[3]: https://travis-ci.org/facebook/react-native
[4]: http://circleci.com/gh/facebook/react-native
[5]: https://github.com/facebook/react-native/blob/master/CONTRIBUTING.md#pull-requests
Closes https://github.com/facebook/react-native/pull/14067

Differential Revision: D5125660

Pulled By: hramos

fbshipit-source-id: e0487c5ca51ffae3955e7057f9afcfa84e10d76b

website/showcase.json

@@ -105,8 +105,8 @@
   {
     "name": "Discord",
     "icon": "http://a5.mzstatic.com/us/r30/Purple5/v4/c1/2f/4c/c12f4cba-1d9a-f6bf-2240-04085d3470ec/icon175x175.jpeg",
-    "linkAppStore":  "https://itunes.apple.com/us/app/discord-chat-for-gamers/id985746746?mt=8",
-    "infoLink": "https://discord.engineering/react-native-deep-dive-91fd5e949933#.5jnqftgof",
+    "linkAppStore": "https://itunes.apple.com/us/app/discord-chat-for-gamers/id985746746?mt=8",
+    "infoLink": "https://blog.discordapp.com/using-react-native-one-year-later-91fd5e949933",
     "infoTitle": "Using React Native: One Year Later",
     "pinned": true
   },