Fixing typo in introduction.Rmd (#1026)

introduction.Rmd

@@ -93,7 +93,7 @@ Pick and choose between the chapters as the various topics come up in your devel
 
 First we cover key package components: @sec-r discusses where your code lives and how to organize it, @sec-data shows you how to include data in your package, and @sec-misc covers a few less important files and directories that need to be discussed somewhere.
 
-Next we'll dive into to the package metadata, starting with `DESCRIPTION` in @sec-description.
+Next we'll dive into the package metadata, starting with `DESCRIPTION` in @sec-description.
 We'll then go deep into dependencies.
 In @sec-dependencies-mindset-background, we'll cover the costs and benefits of taking on dependencies and provide some technical background on package namespaces and the search path.
 In @sec-dependencies-in-practice, we focus on practical matters, such as how to use different types of dependencies in different parts of your package.