Doc: add explanation on Qt Quick and Widgets

Change-Id: Icd08d1546c49c7b00d2afc2c0b9b20f56bcb9bb5
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

doc/src/getting-started/gettingstarted.qdoc

@@ -94,15 +94,19 @@
 
     \section1 Create Your First Applications
 
-    Learn the basics of Qt and Qt Quick development by following two tutorials
-    that illustrate how to create simple applications and build and run them on
+    Learn the basics of Qt and Qt Quick development by following the two tutorials
+    below that illustrate how to create simple applications and build and run them on
     target platforms:
-
     \list
     \li \l {Getting Started Programming with Qt Widgets}
     \li \l {Getting Started Programming with Qt Quick}
     \endlist
 
+    \l{Qt Widgets} provides a library of UI elements which allow you to
+    create classic desktop-style user interfaces. \l {Qt Quick} is a library
+    providing types and functionalities for building modern, fluid, animated
+    UIs.
+
     For a more thorough walkthrough of the different aspects of developing
     applications with Qt 5, see the \l {QML Book}. It focuses on Qt Quick,
     but also provides the information needed to use QML together with C++.