Make change as per reviewer's suggestion

Co-Authored-By: Lia Corrales <lia.astro@gmail.com>

Author: kakirastern

tutorials/notebooks/FITS-tables/FITS-tables.ipynb

@@ -10,7 +10,7 @@
     "Lia Corrales, Kris Stern\n",
     "\n",
     "## Learning Goals\n",
-    "1. Learn how to open the FITS file and view table contents\n",
+    "1. Learn how to open a FITS file and view table contents\n",
     "2. Learn how to make a 2-D histogram with some table data\n",
     "3. Learn how to close the FITS file after use\n",
     "\n",