A fix for npmlog error

Summary:
Added a fix to the GettingStarted guide, for when npmlog module isn't found.
Solution copied from: tj/n#101 (comment)
Closes #8994

Differential Revision: D3612345

Pulled By: JoelMarcey

fbshipit-source-id: 10e7381adc530bb97c795cae022da3525745122a

Author: GevaZeichner

docs/GettingStarted.md

@@ -93,6 +93,8 @@ npm install -g react-native-cli
 
 If you get a permission error, try with sudo: `sudo npm install -g react-native-cli`.
 
+If you get error `Cannot find module 'npmlog'`, try this before: `curl -0 -L http://npmjs.org/install.sh | sudo sh`.
+
 <block class="mac ios" />
 
 The easiest way to install Xcode is via the [Mac App Store](https://itunes.apple.com/us/app/xcode/id497799835?mt=12).