clarify output is not submitted with form

[estelle]

this has to be listed somewhere.

The form attribute is used to explicitly associate the output element with its form owner. The name attribute represents the element's name. The output element is associated with a form so that it can be easily referenced from the event handlers of form controls; the element's value itself is not submitted when the form is submitted.

from https://html.spec.whatwg.org/multipage/form-elements.html#the-output-element

[github-actions]

Preview URLs

• /en-US/docs/Web/HTML/Element/output