himedlooff

var $dif = $('.js-details-container');

$dif.each(function(index){

	$thisDif = $(this);
	$buttons = $thisDif.find('.meta .actions .button-group');
	$review = $('<a href="#" class="button minibutton diff-review">Mark as reviewed<code></code></a>');
	$collapse = $('<a href="#" class="button minibutton diff-collapse">Collapse<code></code></a>');

	$buttons.append($review);

himedlooff

<a href="#" class="btn">Anchor Tag</a>
<button class="btn">Button Tag</button>
<input type="submit" value="Input Tag" class="btn" />