Update tutorials/FITS-images/FITS-images.ipynb

Co-authored-by: Matt Craig <mattwcraig@gmail.com>

Author: HarrisChenchen

tutorials/FITS-images/FITS-images.ipynb

@@ -19,7 +19,7 @@
     "\n",
     "## Companion Content\n",
     "\n",
-    "* This link provides a comprehensive description about FITS file usage in this tutorial: [astropy.io.fits](http://docs.astropy.org/en/stable/io/fits/index.html) \n",
+    "* This link provides a comprehensive description of FITS file usage in this tutorial: [astropy.io.fits](http://docs.astropy.org/en/stable/io/fits/index.html) \n",
     "\n",
     "## Keywords\n",
     "FITS, file input/output, image manipulation, numpy, matplotlib, histogram, colorbar\n",