corrected decoding targets in tutorial
"In this example, we will use a convolutional neural network on the [Physiobank EEG Motor Movement/Imagery Dataset](https://www.physionet.org/physiobank/database/eegmmidb/) to decode two classes:\n",
"\n",
"1. Executed and imagined opening and closing of both hands\n",
- "2. Executed and imagined opening and closing of both fists\n",
+ "2. Executed and imagined opening and closing of both feet\n",
"\n",
"<div class=\"alert alert-warning\">\n",
"\n",
