title: React Formik checkbox group does not turn into an array of invidual checked or unchecked elements
body: <p>I am using Formik to create a form on a website. In this form I have a set of tags which I want to be checkable with individual checkboxes, but keep them in an array <code>tags</code>. Formik claims to be able to do so by using the same <code>name</code> attribute on the Field elements, but I can not get it to work.</p>
  
  <p>I am using this <a href="https://github.com/jaredpalmer/formik/blob/master/examples/Checkbox.js" rel="noreferrer">code example</a> as an reference.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>import React from "react";
  import ReactDOM from "react-dom";
  import { Formik, Form, Field } from "formik";
  
  import "./styles.css";
  
  function App() {
    return (
      &lt;div className="App"&gt;
        &lt;h1&gt;Hello CodeSandbox&lt;/h1&gt;
        &lt;h2&gt;Start editing to see some magic happen!&lt;/h2&gt;
        &lt;ProjectsForm /&gt;
      &lt;/div&gt;
    );
  }
  
  const ProjectsForm = props =&gt; (
    &lt;Formik
      initialValues={{
        search: "",
        tags: []
      }}
      onSubmit={values =&gt; {
        console.log(values);
      }}
      validate={values =&gt; {
        console.log(values);
      }}
      validateOnChange={true}
    &gt;
      {({ isSubmitting, getFieldProps, handleChange, handleBlur, values }) =&gt; (
        &lt;Form&gt;
          &lt;Field type="text" name="search" /&gt;
          &lt;label&gt;
            &lt;Field type="checkbox" name="tags" value="one" /&gt;
            One
          &lt;/label&gt;
          &lt;label&gt;
            &lt;Field type="checkbox" name="tags" value="two" /&gt;
            Two
          &lt;/label&gt;
          &lt;label&gt;
            &lt;Field type="checkbox" name="tags" value="three" /&gt;
            Three
          &lt;/label&gt;
        &lt;/Form&gt;
      )}
    &lt;/Formik&gt;
  );
  
  const rootElement = document.getElementById("root");
  ReactDOM.render(&lt;App /&gt;, rootElement);
  </code></pre>
  
  <p>Also on <a href="https://codesandbox.io/s/jolly-frog-4u8w1" rel="noreferrer">CodeSandbox</a></p>
  
  <p>I am expecting to receive thought the <code>console.log(values)</code> to display something like:</p>
  
  <p><code>Object {search: "", tags: ['one', 'three']}</code></p>
  
  <p>or</p>
  
  <p><code>Object {search: "", tags: ['one': true, 'two': false, 'three': true]}</code></p>
  
  <p>Hope there is a simple thing I am missing to add the Formik checkbox group functionality, as it claims to be possible.</p>