code: function generateHeadingSelector(headingIndexingLevel) {
    let headingsSelector = 'h1';
    for (let i = 2; i <= headingIndexingLevel; i += 1) {
      headingsSelector += `, h${i}`;
    }
    return headingsSelector;
  }
docs: Generates a heading selector based on the indexing level
  @param headingIndexingLevel to generate