avoid references to fiel out of directory

request for packaging, it would be nice for example not to reference
files outside of exampel directory
copy ../../_static/logo.png in logo/logo.png
use subfolder for demo purpose of targetting subfolder in
demo notebook

docs/examples/notebooks/00_notebook_tour.ipynb

@@ -404,7 +404,7 b''
      "collapsed": false,
      "input": [
       "from IPython.display import Image\n",
-      "Image(filename='../../source/_static/logo.png')"
+      "Image(filename='logo/logo.png')"
      ],
      "language": "python",
      "metadata": {},