Describe in syntax doc that setting @context to null resets the state of the local context.
--- a/spec/latest/json-ld-syntax/index.html Mon Apr 09 13:31:28 2012 -0700
+++ b/spec/latest/json-ld-syntax/index.html Mon Apr 09 13:41:26 2012 -0700
@@ -677,7 +677,8 @@
<p>
The set of contexts defined within a specific <tref>JSON Object</tref> are
- referred to as <tdef>local context</tdef>s. The
+ referred to as <tdef>local context</tdef>s. Setting the context to <code>null</code>
+ effectively sets the <tdef>local context</tdef> to it's initial state. The
<tdef>active context</tdef> refers to the accumulation of
<tref>local context</tref>s that are in scope at a specific point within
the document. The following example specifies an external context and then