Remove deprecated Gen2 Butler comment

Author: kadrlica

03_Image_Display_and_Manipulation.ipynb

@@ -202,10 +202,6 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "# Note that the keys are slightly different for DC2/LSSTCam\n",
-    "# You can view all the keys by creating the butler and calling:\n",
-    "#   print(butler.getKeys('calexp'))\n",
-    "\n",
     "dataId = {'visit': 192350, 'detector': 175, 'band': 'i'}\n",
     "# Note: because the combination of visit+detector already uniquely identifies\n",
     "# the exposure, specifying \"band\" above is unnecessary.\n",