fixes #27

intro.tex

@@ -198,10 +198,10 @@ \section{What Is an Operating System?}\label{what-is-os-section}
 and may not be available for separate purchase.
 
 For example, Microsoft Windows comes with a user interface known as
-Explorer, which provides features such as the Start menu and the
-ability to click icons.  (This program is distinct from the
-similarly named web browser, Internet Explorer.)  However, even if you
-are an experienced Windows user, you may never have heard of Explorer;
+File Explorer, which provides features such as the Start menu and the
+ability to click icons.  (This program was named Windows Explorer prior
+to Windows 8.) However, even if you
+are an experienced Windows user, you may never have heard of File Explorer;
 Microsoft has chosen to give it a very low profile, treating it as an
 integral part of the Microsoft Windows environment.  At a technical
 level, however, it is distinct from the operating system proper.  In