brief preambles for each application

_includes/tutorial/html-ui.md

@@ -2,7 +2,7 @@
 
 ![HTML UI Screenshot](screenshots/html-ui.png)
 
-To run the example type: 
+The HTML UI application demonstrates defining a Shiny user-interface using a standard HTML page rather than a ui.R script. To run the example type: 
 
 <pre><code class="console">&gt; library(shiny)
 &gt; runExample(&quot;08_html&quot;)

_includes/tutorial/more-widgets.md

@@ -2,7 +2,7 @@
 
 ![More Widgets Screenshot](screenshots/more-widgets.png)
 
-To run the example type: 
+The More Widgets application demonstrates the helpText and submitButton widgets as well as the use of embedded HTML elements to customized formatting. To run the example type: 
 
 <pre><code class="console">&gt; library(shiny)
 &gt; runExample(&quot;07_widgets&quot;)

_includes/tutorial/reactivity.md

@@ -2,13 +2,14 @@
 
 ![Reactivity Screenshot](screenshots/reactivity.png)
 
-
-To run the example type: 
+The Reactivity application is very similar to Hello Text but goes into much more detail about reactive programming concepts. To run the example type: 
 
 <pre><code class="console">&gt; library(shiny)
 &gt; runExample(&quot;03_reactivity&quot;)
 </code></pre>
 
+Try changing the text in the Caption field to something else--you'll notice that the caption is updated immediately in the output pane. 
+
 #### ui.R
 
 <pre><code class="r">library(shiny)

_includes/tutorial/shiny-text.md

@@ -1,7 +1,7 @@
 
 ![Tabsets Screenshot](screenshots/shiny-text.png)
 
-To run the example type: 
+The Shiny Text application demonstrates printing R objects directly as well as displaying data-frames using HTML tables. To run the example type: 
 
 <pre><code class="console">&gt; library(shiny)
 &gt; runExample(&quot;02_text&quot;)

_includes/tutorial/sliders.md

@@ -2,7 +2,7 @@
 
 ## (Under Construction)
 
-To run the example type: 
+The Sliders application demonstrates the many capabilities of slider controls, including the ability to run an animation sequence. To run the example type: 
 
 <pre><code class="console">&gt; library(shiny)
 &gt; runExample(&quot;05_sliders&quot;)

_includes/tutorial/tabsets.md

@@ -2,7 +2,7 @@
 
 ![Tabsets Screenshot](screenshots/tabsets.png)
 
-To run the example type: 
+The Tabsets application demonstrates using tabs to present output. To run the example type: 
 
 <pre><code class="console">&gt; library(shiny)
 &gt; runExample(&quot;06_tabsets&quot;)