Added astroquery install instructions

notebooks/acs_subarrays.ipynb

@@ -47,7 +47,15 @@
     "\n",
     "2. Post-SM4: As discussed above, differences in the clocking rate between subarray and full-frame observations taken after SM4 require subarray data to have corresponding bias frames taken with the same subarray readout definitions to create the superbias image.\n",
     "\n",
-    "The [CRDS](https://hst-crds.stsci.edu) is unable to match appropriately sized superbias reference files to custom subarray images. In cases where such a reference file is required, users will need to either create it themselves or contact the ACS Team via the [help desk](http://hsthelp.stsci.edu) for assistance."
+    "The [CRDS](https://hst-crds.stsci.edu) is unable to match appropriately sized superbias reference files to custom subarray images. In cases where such a reference file is required, users will need to either create it themselves or contact the ACS Team via the [help desk](http://hsthelp.stsci.edu) for assistance.\n",
+    "\n",
+    "<div class=\"alert alert-warning\">Before running these examples, be sure to update you [AstroConda](https://astroconda.readthedocs.io/en/latest/) distribution to the lastest version. You will also need to install `astroquery` via:\n",
+    "<br><br>\n",
+    "```\n",
+    "conda install astroquery\n",
+    "```\n",
+    "<br><br>\n",
+    "which will allow you to download the datasets used in these examples.</div>"
    ]
   },
   {