Add Installation to section overview

CONTRIBUTING.md

@@ -14,6 +14,8 @@ so that you can understand what actions will and will not be tolerated.
 
 The documentation is divided into sections to cater to different learning styles and use cases. When editing an article, try to match the surrounding text in tone and style. When creating a new article, try to match the tone of the other articles in the same section. Learn about the motivation behind each section below.
 
+**[Installation](https://reactjs.org/docs/getting-started.html)** gives an overview of the docs, and demonstrates two different ways to use it: either as a simple `<script>` tag on the page, or as part of a complex JavaScript toolchain.
+
 **[Tutorial](https://reactjs.org/tutorial/tutorial.html)** is relatively informal, and is designed for people who prefer a hands-on approach to learning, and can tolerate skipping theory in favor of practice. Its goal is to give the reader a feel for a typical React workflow rather than to explain fundamentals in detail. Here we focus on *what* to do and spend less time on *how* or *why* we did it. It is extremely important to do a lot of hand-holding and unambiguously describe every single change. It should be possible for a beginner to mechanically follow every instruction, and still get to a working tic-tac-toe game.
 
 **[Main Concepts](https://reactjs.org/docs/hello-world.html)** is designed to introduce fundamental concepts in a step-by-step way. Each individual article in Main Concepts builds on the knowledge from the previous ones, so make sure not to add any "cyclical dependencies" between them. It is important that the reader can start with the first article and work their way to the last Main Concepts article without ever having to "look ahead" for a definition. This explains some ordering choices (e.g. that state is explained before events, or that "thinking in React" doesn't use refs). Main Concepts also serves as a reference manual for React concepts, so it is important to be very strict about their definitions and relationships between them. This is, for example, why we introduce elements before components. Resist adding too much detail to Main Concepts articles. They intentionally don't cover all corner cases, and focus on establishing firm foundations.