Fix wording of nested properties.

Fixes #235.

Author: gkellogg

index.html

@@ -1656,7 +1656,7 @@ <h1>Advanced Concepts</h1>
     further discussion.</p></dd>
   <dt>Property nesting</dt>
   <dd><p>Another JSON idiom often found in APIs is to use an
-      intermediate object to represent the properties of an object; in JSON-LD
+      intermediate object to to group together related properties of an object; in JSON-LD
       these are referred to as <a>nested properties</a> and are described in <a
       href="#nested-properties" class="sectionRef"></a>.</p></dd>
   <dt>Referencing objects</dt>