Mention correct shortcut to open "Developer Tools"

Summary:
`⌘⌥J` is for "JavaScript Console", `⌘⌥I` is for "Developer Tools"

The shortcut mentioned was for opening the "JavaScript Console", which is incorrect.

![image](https://cloud.githubusercontent.com/assets/351038/25304378/4e210808-2766-11e7-8a6b-b1d1a160bc42.png)
Closes https://github.com/facebook/react-native/pull/13628

Differential Revision: D5700784

Pulled By: hramos

fbshipit-source-id: 668e2861dbece7eabc776202cee37759f6ca3099

local-cli/server/util/debugger.html

@@ -248,7 +248,7 @@
     <p>
       React Native JS code runs as a web worker inside this tab.
     </p>
-    <p>Press <kbd id="shortcut" class="shortcut">⌘⌥J</kbd> to open Developer Tools. Enable <a href="https://stackoverflow.com/a/17324511/232122" target="_blank">Pause On Caught Exceptions</a> for a better debugging experience.</p>
+    <p>Press <kbd id="shortcut" class="shortcut">⌘⌥I</kbd> to open Developer Tools. Enable <a href="https://stackoverflow.com/a/17324511/232122" target="_blank">Pause On Caught Exceptions</a> for a better debugging experience.</p>
     <p>You may also install <a href="https://github.com/facebook/react-devtools/tree/master/packages/react-devtools" target="_blank">the standalone version of React Developer Tools</a> to inspect the React component hierarchy, their props, and state.</p>
     <p>Status: <span id="status">Loading...</span></p>
   </div>