setting the header-data-theme to swatch b for consistency otherwise it defaults to swatch a,

fixing copy/paste typo at collapsible content description

Author: MauriceG

docs/pages/pages-themes/theme-b.html

@@ -15,7 +15,7 @@
 
 	<div data-role="page" class="type-interior" data-theme="b">
 
-		<div data-role="header">
+		<div data-role="header" data-theme="b">
 		<h1>Theming pages</h1>
 		<a href="../../../" data-icon="home" data-iconpos="notext" data-direction="reverse" class="ui-btn-right jqm-home">Home</a>
 	</div><!-- /header -->
@@ -100,7 +100,7 @@ <h2>Collapsible Sets</h2>
 					<div data-role="collapsible-set">
 						<div data-role="collapsible" data-collapsed="false">
 							<h3>Section 1</h3>
-							<p>I'm the collapsible content in a set so this feels like an accordion. I'm hidden by default because I have the "collapsed" state; you need to expand the header to see me.</p>
+							<p>I'm the collapsible content in a set so this feels like an accordion. I'm visible by default because I have the <code>data-collapsed="false"</code> attribute; to collapse me, either click my header or expand another header in my set.</p>
 						</div>
 						<div data-role="collapsible">
 							<h3>Section 2</h3>