Update Android support URL

Summary:
> Explain the **motivation** for making this change. What existing problem does the pull request solve?

There's no longer a seaprate page for Android setup instructions, it just redirects to the getting started page, where you have to navigate futher.

**Test plan (required)**

None.
Closes https://github.com/facebook/react-native/pull/10524

Differential Revision: D4069696

Pulled By: lacker

fbshipit-source-id: 67f6450f550cbbf446476ea824a6915125e823ba

local-cli/runAndroid/runAndroid.js

@@ -116,8 +116,9 @@ function buildAndRun(args) {
     console.log(chalk.red(
       'Could not install the app on the device, read the error above for details.\n' +
       'Make sure you have an Android emulator running or a device connected and have\n' +
-      'set up your Android development environment:\n' +
-      'https://facebook.github.io/react-native/docs/android-setup.html'
+      'set up your Android development environment.\n' +
+      'Go to https://facebook.github.io/react-native/docs/getting-started.html\n' +
+      'and check the Android tab for setup instructions.'
     ));
     // stderr is automatically piped from the gradle process, so the user
     // should see the error already, there is no need to do