Update usage notes for [de]serialisation.

README.md

@@ -23,6 +23,16 @@ Usage
     bloom.test("bar");
     bloom.test("blah");
 
+    // Serialisation. Note that bloom.buckets may be a typed array,
+    // so we convert to a normal array first.
+    var array = [].slice.call(bloom.buckets),
+        json = JSON.stringify(array);
+
+    // Deserialisation. Note that the any array-like object is supported, but
+    // this will be used directly, so you may wish to use a typed array for
+    // performance.
+    var bloom = new BloomFilter(array, 3);
+
 Implementation
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