update samples from Release-86 as a part of 1.28.0 SDK stable release

tutorials/image-classification-mnist-data/img-classification-part1-training.ipynb

@@ -128,6 +128,9 @@
       "metadata": {},
       "source": [
         "### Create or Attach existing compute resource\n",
+        "\n",
+        "> Note that if you have an AzureML Data Scientist role, you will not have permission to create compute resources. Talk to your workspace or IT admin to create the compute targets described in this section, if they do not already exist.\n",
+        "\n",
         "By using Azure Machine Learning Compute, a managed service, data scientists can train machine learning models on clusters of Azure virtual machines. Examples include VMs with GPU support. In this tutorial, you create Azure Machine Learning Compute as your training environment. You will submit Python code to run on this VM later in the tutorial. \n",
         "The code below creates the compute clusters for you if they don't already exist in your workspace.\n",
         "\n",