[css-content] expand intro to section 2

Author: dauwhe

css-content/Overview.bs

@@ -135,7 +135,9 @@ Issue: should the contents keyword be replaced with ''content()''
 <h2 id="content-functions">
 Content Values and Functions</h2>
 
-	There are many ways of adding content to a document via the ''content'' property. This section describes them.
+	The ''content'' property can be used to add many different types of content to a document,
+    including images, strings, the values of counters, and the text value of elements. 
+    In this section we enumerate the possibilities. 
 
 	Issue: write better introduction to this section
 
@@ -722,7 +724,7 @@ a::after { content: ", in the chapter entitled " target-text(attr(href url)) }
 <h3 id="named-strings-heading">
 Named strings</h3>
 
-CSS3 introduces <dfn>named strings</dfn>, which are the textual equivalent of counters and which have a distinct namespace from counters. Named strings follow the same nesting rules as counters. The 'string-set' property accepts values similar to the 'content' property, including the extraction of the current value of counters.
+This section introduces <dfn>named strings</dfn>, which are the textual equivalent of counters and which have a distinct namespace from counters. Named strings follow the same nesting rules as counters. The 'string-set' property accepts values similar to the 'content' property, including the extraction of the current value of counters.
 
 Named strings are a convenient way to pull metadata out of the document for insertion into headers and footers. In HTML, for example, META elements contained in the document HEAD can set the value of named strings. In conjunction with attribute selectors, this can be a powerful mechanism: