Fix grammar in Imported Contexts section.

Fixes #244.

Author: gkellogg

index.html

@@ -3662,8 +3662,8 @@ <h3>Using the Document Base for the Default Vocabulary</h3>
     additional type coercion information.</p>
 
   <p>The following examples illustrate how `@import` can be used to express
-    a for <a>type-scoped context</a> that loads an imported <a>context</a> and
-    sets `@propagate` to `true` and how to make similar modifications.</p>
+    a <a>type-scoped context</a> that loads an imported <a>context</a> and
+    sets `@propagate` to `true`, as a technique for making other similar modifications.</p>
 
   <p>Suppose there was a <a>context</a> that could be referenced remotely
     via the URL <code>https://json-ld.org/contexts/remote-context.jsonld</code>:</p>