Update plot-catalog.ipynb

added description.

Author: kelle

tutorials/Plot-Catalog/plot-catalog.ipynb

@@ -1,11 +1,12 @@
 {
  "metadata": {
   "astropy-tutorials": {
-   "author": "Adrian M. Price-Whelan <adrn@astro.columbia.edu>",
+   "author": "Adrian M. Price-Whelan <adrn@astro.columbia.edu> and Kelle Cruz <kellecruz@gmail.com>",
    "date": "July 2013",
    "link_name": "Read and plot catalog information from a text file",
    "name": "",
    "published": true
+   "description" : "Demonstrates use of astropy.io.ascii for reading and writing ASCII data, astropy.coordinates and astropy.units for converting RA (as a sexagesimal angle) to decimal degrees, and matplotlib for making a color-magnitud diagram and on-sky locations in a mollweide projection."
   },
   "signature": "sha256:a6948119e622634bad34bb4d1b7bcbb59e84cab95025724098127104a63cc42c"
  },
@@ -444,4 +445,4 @@
    "metadata": {}
   }
  ]
-}
+}