Clarification, where does `data-sketch-colors` appear in Sketch?
With this code:

    <div class="gb-row" data-sketch-symbol="Colors/Main">
      <div class="gb-col-12--xs">
        <div class="rlx-palette">
          ...
          <div class="rlx-palette-itemHolder">
            <strong class="rlx-palette-itemText">Crème brûlée, <em>#FFE49C</em></strong>
            <div class="rlx-palette-item rlx-color rlx-color-brand rlx-color-yellow" data-sketch-color="#FFE49C"></div>
          </div>
          ...
        </div>
      </div>
    </div>

Where does the colors appear in sketch? The symbol Colors/Main appears, but I can't see to locate where the colors are at. If I check "document colors" in the right pane for an element, it is empty.