HTTP Post footprint change

No we require either a body, or a null/undefined
Closes #520

snippets/httpPost.md

@@ -10,7 +10,7 @@ Omit the third argument, `data`, to send no data to the provided `url`.
 Omit the fourth argument, `err`, to log errors to the console's `error` stream by default.
 
 ```js
-const httpPost = (url, callback, data = null, err = console.error) => {
+const httpPost = (url, data, callback, err = console.error) => {
   const request = new XMLHttpRequest();
   request.open('POST', url, true);
   request.setRequestHeader('Content-type', 'application/json; charset=utf-8');
@@ -30,8 +30,8 @@ const newPost = {
 const data = JSON.stringify(newPost);
 httpPost(
   'https://jsonplaceholder.typicode.com/posts',
-  console.log,
-  data
+  data,
+  console.log
 ); /*
 Logs: {
   "userId": 1,
@@ -40,4 +40,13 @@ Logs: {
   "body": "bar bar bar"
 }
 */
+httpPost(
+  'https://jsonplaceholder.typicode.com/posts',
+  null,
+  console.log
+); /*
+Logs: {
+  "id": 101
+}
+*/
 ```