Update workflow notebook

Author: Joeri Hermans

examples/workflow.ipynb

@@ -58,7 +58,7 @@
     "# Modify these variables according to your needs.\n",
     "application_name = \"Distributed Keras Experimentation\"\n",
     "using_spark_2 = False\n",
-    "yarn = \"p01001532067275.cern.ch:8088\" # Address:port of ResourceManager\n",
+    "yarn = \"YARN_URI\" # Address:port of ResourceManager\n",
     "if not yarn:\n",
     "    # Tell master to use local resources.\n",
     "    master = \"local[*]\"\n",