title: matplotlib mark out only the highest bar with its frequency value in histogram
body: <p>I would like to mark out the highest bar with its frequency value in a histogram created by matplotlib in python 3.7.</p>
  <p>The data is dataframe of pandas.</p>
  <p>Just like in this figure,
  <a href="https://stackoverflow.com/questions/43374920/how-to-automatically-annotate-maximum-value-in-pyplot">How to automatically annotate maximum value in pyplot?</a></p>
  <p>but, my plot is histogram. I do not want to mark each bar with its value.</p>