Add Installation link to jupyter notebook tutorial

Also use the url link to github because *.md files are not
rendered when using jupyter notebook

object_detection/object_detection_tutorial.ipynb

@@ -5,7 +5,7 @@
    "metadata": {},
    "source": [
     "# Object Detection Demo\n",
-    "Welcome to the object detection inference walkthrough!  This notebook will walk you step by step through the process of using a pre-trained model to detect objects in an image."
+    "Welcome to the object detection inference walkthrough!  This notebook will walk you step by step through the process of using a pre-trained model to detect objects in an image. Make sure to follow the [installation instructions](https://github.com/tensorflow/models/blob/master/object_detection/g3doc/installation.md) before you start."
    ]
   },
   {
@@ -96,7 +96,7 @@
     "\n",
     "Any model exported using the `export_inference_graph.py` tool can be loaded here simply by changing `PATH_TO_CKPT` to point to a new .pb file.  \n",
     "\n",
-    "By default we use an \"SSD with Mobilenet\" model here. See the [detection model zoo](g3doc/detection_model_zoo.md) for a list of other models that can be run out-of-the-box with varying speeds and accuracies."
+    "By default we use an \"SSD with Mobilenet\" model here. See the [detection model zoo](https://github.com/tensorflow/models/blob/master/object_detection/g3doc/detection_model_zoo.md) for a list of other models that can be run out-of-the-box with varying speeds and accuracies."
    ]
   },
   {