minor edit

python/caffe/imagenet/selective_search_demo.ipynb

@@ -13,7 +13,7 @@
      "source": [
       "First of all, we'll need a little [Python script](https://github.com/sergeyk/selective_search_ijcv_with_python) to run the Matlab Selective Search code.\n",
       "\n",
-      "Let's run detection on an image of a cat lounging on a couch, which we will download from the web.\n",
+      "Let's run detection on an image of a cat lounging on a couch (one of the ImageNet pictures), which we will download from the web.\n",
       "\n",
       "    wget http://farm2.static.flickr.com/1104/1204206441_bc256e34f2.jpg\n",
       "    echo \"1204206441_bc256e34f2.jpg\" > image_cat.txt\n",