Further clarify that @version is a _number_, not a _string_.

Author: gkellogg

spec/latest/json-ld/index.html

@@ -870,7 +870,7 @@ <h2>JSON-LD 1.1 Processing Mode</h2>
   <p>New features defined in JSON-LD 1.1 are available
     when the <a>processing mode</a> is set to <code>json-ld-1.1</code>.
     This may be set using the <code>@version</code> member in a <code>context</code>
-    set to the value <code>1.1</code>, or through an API option.</p>
+    set to the value <code>1.1</code> as a <a>number</a>, or through an API option.</p>
 
   <pre class="example" data-transform="updateExample"
        title="Setting @version in context">