Merge pull request #1655 from plotly/replace-dash-ad

replace logo in dash ad

Author: Joseph Damiba

_includes/layouts/helpbox.html

@@ -7,7 +7,7 @@
  <img
  height="50%"
  width="50%"
- src="https://s3-us-west-1.amazonaws.com/plotly-tutorials/assets/dash-ad.png"
+ src="https://plotly-tutorials.s3-us-west-1.amazonaws.com/assets/dash-ad-2.png"
  />
  </div>
  </div>