Rename "locally cached" to "static copy".

Author: msporny

index.html

@@ -4889,7 +4889,7 @@ <h3>Base Context</h3>
             </li>
             <li>
 The content in a credential whose meaning depends on a link to an external URL,
-such as a JSON-LD Context, which can be secured by using a locally cached copy,
+such as a JSON-LD Context, which can be secured by using a local static copy,
 or a cryptographic digest of the file.
             </li>
           </ol>