title: Add a new key-value pair to a JSON object
body: <p>I am connecting to an API which gives a rather large json payload. I need to add a key and value to the root object.Once I do <code>ioutil.Readall</code> from the package "net/http" the JSON is a byte array. </p>
  
  <p>My goal is to just simply add to the structure and move on. As an example, the following the pretty similar to what I am doing:  <a href="https://tutorialedge.net/golang/consuming-restful-api-with-go/" rel="nofollow noreferrer">https://tutorialedge.net/golang/consuming-restful-api-with-go/</a></p>
  
  <p>So how can I simply add to a JSON structure another element (key: value)?</p>