title: jq read inline string, not from stdin
body: <p>This can read from a file:</p>
  
  <pre><code>jq '.c | fromjson | .id' my_file.json
  </code></pre>
  
  <p>this reads from stdin:</p>
  
  <pre><code>echo "$my_json" | jq -r '.field'
  </code></pre>
  
  <p>what if I just want to read from a string like so:</p>
  
  <pre><code>jq '.field' "$my_json"
  </code></pre>
  
  <p>how to do that?</p>