Update FITS-tables.ipynb

Author: kakirastern

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

@@ -15,7 +15,7 @@
     "3. Learn how to close the FITS file after use\n",
     "\n",
     "## Keywords\n",
-    "table, file input/output, matplotlib, FITS table\n",
+    "table, file input/output (i/o), matplotlib, FITS table\n",
     "\n",
     "## Summary\n",
     "\n",