Merge pull request #24 from microsoft/mjm/add-pcdc

Add link to data catalog repo

Author: mmcfarland

README.md

@@ -18,6 +18,7 @@ The Planetary Computer has open sourced a number of its components, which you wi
 
 - [Planetary Computer APIs](https://github.com/microsoft/planetary-computer-apis)
 - [Planetary Computer Containers](https://github.com/microsoft/planetary-computer-containers)
+- [Planetary Computer Data Catalog](https://github.com/microsoft/PlanetaryComputerDataCatalog)
 - [Planetary Computer Hub](https://github.com/microsoft/planetary-computer-hub)
 - [Planetary Computer Examples](https://github.com/microsoft/PlanetaryComputerExamples)
 - [Planetary Computer Python package](https://github.com/microsoft/planetary-computer-sdk-for-python)