Adds links to the readme

Author: garrettgman

README.md

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 [![Travis build status](https://travis-ci.org/rstudio-education/hopr.svg?branch=master)](https://travis-ci.org/rstudio-education/hopr)
 
 <a href="https://www.amazon.com/Hands-Programming-Write-Functions-Simulations/dp/1449359019"><img src="cover.png" width="285" height="375" alt="Cover image" align="right" style="margin: 0 1em 0 1em" /></a> This is the website for __"Hands-On Programming with R"__. This book will teach you how to program in R, with hands-on examples. I wrote it for non-programmers to provide a friendly introduction to the R language. You'll learn how to load data, assemble and disassemble data objects, navigate R's environment system, write your own functions, and use all of R's programming tools. Throughout the book, you'll use your newfound skills to solve practical data science problems.
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+Read the free online copy [here](https://rstudio-education.github.io/hopr).
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+Purchase a hard copy [here](https://www.amazon.com/Hands-Programming-Write-Functions-Simulations/dp/1449359019).