title: Drupal 8 create field programmatically
body: <p>I created a custom module for Drupal 8 that allows the users to choose a Content type in order to add some fields programmatically.
  How I can create some fields (text type in this case) and attach they to a Content type with a custom module?</p>
  <p>Some help?</p>
  <p>Thanks.</p>