Update README.md

Removed old instruction links.

Author: aszk

README.md

@@ -3,8 +3,6 @@ Build An Alexa Quiz Skill in Python using ASK Python SDK
 
 ![Tutorial Header](https://m.media-amazon.com/images/G/01/mobile-apps/dex/alexa/alexa-skills-kit/tutorials/fact/header._TTH_.png)
 
-[![Voice User Interface](https://m.media-amazon.com/images/G/01/mobile-apps/dex/alexa/alexa-skills-kit/tutorials/navigation/1-on._TTH_.png)](./instructions/1-voice-user-interface.md)[![Lambda Function](https://m.media-amazon.com/images/G/01/mobile-apps/dex/alexa/alexa-skills-kit/tutorials/navigation/2-off._TTH_.png)](./instructions/2-lambda-function.md)[![Connect VUI to Code](https://m.media-amazon.com/images/G/01/mobile-apps/dex/alexa/alexa-skills-kit/tutorials/navigation/3-off._TTH_.png)](./instructions/3-connect-vui-to-code.md)[![Testing](https://m.media-amazon.com/images/G/01/mobile-apps/dex/alexa/alexa-skills-kit/tutorials/navigation/4-off._TTH_.png)](./instructions/4-testing.md)[![Customization](https://m.media-amazon.com/images/G/01/mobile-apps/dex/alexa/alexa-skills-kit/tutorials/navigation/5-off._TTH_.png)](./instructions/5-customization.md)[![Publication](https://m.media-amazon.com/images/G/01/mobile-apps/dex/alexa/alexa-skills-kit/tutorials/navigation/6-off._TTH_.png)](./instructions/6-publication.md)
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 ## What You Will Learn
 *  [AWS Lambda](http://aws.amazon.com/lambda)
 *  [Alexa Skills Kit (ASK)](https://developer.amazon.com/alexa-skills-kit)