Fix typo

src/introduction.md

@@ -4,4 +4,4 @@ This website holds the documentation for TourForge, an open source set of softwa
 
 The TourForge tour builder, located at <https://tourforge.github.io/builder/>, is a web application that provides a simple interface to build the tour data files that are used by TourForge Guide. A work-in-progress tutorial on how to use TourForge is available in our guide on [using the tour builder](using-tour-builder.md).
 
-TourForge Guide is a Flutter library providing a baseline with the majority of features needed by a tour guide application. Although almost all of the has already been done for you, building your app with the TourForge Guide library still requires some software engineering knowledge (or a lot of patience). You will need to [set up your development environment](development-environment.md) and follow the guide on [building an app](building-app.md).
+TourForge Guide is a Flutter library providing a baseline with the majority of features needed by a tour guide application. Although almost all of the work has already been done for you, building your app with the TourForge Guide library still requires some software engineering knowledge (or a lot of patience). You will need to [set up your development environment](development-environment.md) and follow the guide on [building an app](building-app.md).