Add the summary to the Ch02 index page

ch02-bigpicture-files/index.html

@@ -34,6 +34,13 @@ <h1>
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     <div id="intro" class="columns">
+      <p>
+        As with HTML, CSS, and the other standards that make up the web, the development of SVG has been a process of back-and-forth compromises between the authors of specifications, the builders of web browsers that implement them, and the designers of web pages that use them. Unlike those other languages, however, the SVG specification did not develop slowly and incrementally—​it was created fully formed, as an incredibly complex graphics language.</p>
+      <p>
+        If you work with HTML and CSS web design, you will find many aspects of SVG familiar—​and a few quite different. The SVG standard was built upon other web standards, most notably XML and CSS, and has a complex DOM that can be manipulated with JavaScript. In that way, it is very similar to HTML. But because the primary focus of SVG is graphics, not text, it intersects and connects the parts of the web platform that you usually try to keep separate: content, formatting, and functionality.</p>
+      <p>
+        This chapter starts with a refresher about the main web languages and their separate roles. It then looks at how SVG interacts with these languages. We adapt the stoplight example from <a href="../ch01-overview-files/">Chapter 1</a> to show how you can build on a simple SVG to create complete web pages.
+      </p>
     </div>
     <h2 id="examples">Figures and Examples<a href="#examples" class="hash-link" aria-label="Permalink">#</a></h2>
     <p>The file names link to the code view on GitHub. <em>Beware: the linked screenshots are hi-resolution; some have very large file sizes.</em></p>