Updated tool name and fixed frozen misspelling. (onnx#101)

Author: CPerry26

tutorials/OnnxTensorflowExport.ipynb

@@ -28,7 +28,7 @@
  "Secondly, we freeze the graph. Here, we include quotes from Tensorflow documentation about what graph freezing is:\n",
  "> One confusing part about this is that the weights usually aren't stored inside the file format during training. Instead, they're held in separate checkpoint files, and there are Variable ops in the graph that load the latest values when they're initialized. It's often not very convenient to have separate files when you're deploying to production, so there's the freeze_graph.py script that takes a graph definition and a set of checkpoints and freezes them together into a single file.\n",
  "\n",
- "Thus here we build the free_graph tool in Tensorflow source folder and execute it with the information about where the GraphProto is, where the checkpoint file is and where to put the freozen graph. One caveat is that you need to supply the name of the output node to this utility. If you are having trouble finding the name of the output node, please refer to [this article](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/tools/graph_transforms/README.md#inspecting-graphs) for help.\n",
+ "Thus here we build the freeze_graph tool in the Tensorflow source folder and execute it with the information about where the GraphProto is, where the checkpoint file is and where to put the frozen graph. One caveat is that you need to supply the name of the output node to this utility. If you are having trouble finding the name of the output node, please refer to [this article](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/tools/graph_transforms/README.md#inspecting-graphs) for help.\n",
  "```\n",
  "bazel build tensorflow/python/tools:freeze_graph\n",
  "bazel-bin/tensorflow/python/tools/freeze_graph \\\n",