Added an example update handler to the readme.

README.md

@@ -593,6 +593,21 @@ db.atomic("update", "inplace", "foobar",
 });
 ```
 
+Note that the data is sent in the body of the request.  
+An example update handler follows:
+
+``` js
+"updates": {
+  "in-place" : "function(doc, req) {
+      var body  = JSON.parse(req.body);
+      var field = body.field;
+      var value = body.value;
+      var message = 'set '+field+' to '+value;
+      doc[field] = value;
+      return [doc, message];
+  }"
+```
+
 ### db.search(designname, searchname, [params], [callback])
 
 calls a view of the specified design with optional query string additions `params`.