Updated build command for saved_model_cli

Below command for building saved_model_cli is not working  and throwing "Build file not found " error
bazel build tensorflow/python/tools:saved_model_cli
replaced with 
bazel build //tensorflow/python/tools:saved_model_cli .  Attaching Gist for reference. https://colab.sandbox.google.com/gist/mohantym/5f2785f4c21c6b1e3fe9c5958a62418d/tensorflow-ranking.ipynb#scrollTo=Gr24fRLOQVRZ

Author: mohantym

site/en/guide/saved_model.ipynb

@@ -761,7 +761,7 @@
         "additional command to build `saved_model_cli`:\n",
         "\n",
         "```\n",
-        "$ bazel build tensorflow/python/tools:saved_model_cli\n",
+        "$ bazel build //tensorflow/python/tools:saved_model_cli\n",
         "```\n",
         "\n",
         "### Overview of commands\n",