Add max width to the help text and error message in the form item

[twjeffery]

Info

We want an example in our documentation that shows how to limit the max width of helper and error slots inside the Form Item component.

Acceptance Criteria

1. New example in both Form Item and Text
   • Code idea for that example - talk to @twjeffery to get exactly what we want to show it to look like:
   • The point is to use goab-text inside the slot to determine the max width of the slot

<goab-form-item
  label="maxwidth of 400px / helper maxwidth of 100px"
  maxWidth="400px"
>
  <goab-form-item-slot slot="helptext">
    <goab-text size="body-xs" maxWidth="100px">
      This is some helper text let's see how long we can get this. I think we can get it pretty long.
    </goab-text>
  </goab-form-item-slot>
  <goab-input />
</goab-form-item>