language tour: say what the intent and audience are

_tour/tour-of-scala.md

@@ -13,6 +13,15 @@ next-page: basics
 redirect_from: "/tutorials/tour/tour-of-scala.html"
 ---
 
+## Welcome to the tour
+This tour contains bite-sized introductions to the most frequently used features
+of Scala. It is intended for newcomers to the language.
+
+This is just a brief tour, not a full language tutorial. If
+you want that, consider obtaining [a book](/books.html) or consulting
+[other resources](/learn.html).
+
+## What is Scala?
 Scala is a modern multi-paradigm programming language designed to express common programming patterns in a concise, elegant, and type-safe way. It smoothly integrates features of object-oriented and functional languages.
 
 ## Scala is object-oriented ##

index.md

@@ -15,7 +15,7 @@ sections:
         icon: "fa fa-rocket"
         link: /getting-started.html
       - title: "Tour of Scala"
-        description: "Bite-sized introductions to some of the core language concepts."
+        description: "Bite-sized introductions to core language features."
         icon: "fa fa-flag"
         link: /tour/tour-of-scala.html
       - title: "Scala for Java Programmers"