form-text missing in documentation

[klor]

Form documentation: https://getuikit.com/docs/form
Consider also adding it to https://getuikit.com/docs/text.

<span class="form-text"></span>

Sample code:

<form class="uk-form-horizontal" method="POST">

	<div class="uk-margin">
		<label for="inp_created_by" class="uk-form-label uk-text-bold uk-text-muted uk-text-uppercase uk-text-small">
			Created by
		</label>
		<div class="uk-form-controls">
			<input type="hidden" name="created_by" value="jd">
			<span class="form-text">John Doe</span>
		</div>
	</div>

	<div class="uk-margin">
		<div class="uk-form-controls">
			<input type="submit" name="submit" value="Save" class="uk-button uk-button-primary" />
		</div>
	</div>

</form>

Tip: The form element will collapse if you output an empty string as here: <span class="form-text"></span>, you can fix this by outputting a no-breaking space for empty strings: <span class="form-text">&nbsp;</span>