Update Quantities.ipynb

added description.

Author: kelle

tutorials/Quantities/Quantities.ipynb

@@ -8,6 +8,7 @@
    "published": true
   },
   "signature": "sha256:0b60a6688134ca2541d6d959efb64c1fcb1f59665f6690d041fd4511837f7752"
+  "description" : "Demonstrates use of the astropy.units, astropy.constants, and the Quantity object for calculating the mass of a galaxy from its velocity dispersion and determining masses of molecular clouds from CO intensity maps. Includes use of matplotlib for making a histogram and an image with a colorbar. Also includes good practices for using quantities in functions you might distribute to other people."
  },
  "nbformat": 3,
  "nbformat_minor": 0,