title: looking for a side panel which shows related content
body: <p>I am one of the old guys, menu driven. My newly created website has a menu where I want to have accessible the most important pages/posts always.</p>
  <p>If I open such a page (eg. from menu a) then I would like to have a side panel showing all/some of pages/posts which belong to the same categories/keywords.</p>
  <p>does it exist? maybe some plugin? maybe out of the box?</p>