add .gitignore and update README.md
This is the core CUDA component of the DataSketches library. It contains sketching algorithms that can be accessed directly from user applications.
Note that we have parallel core library components for Java, C++, Python, GO, and Rush implementations of many of the same sketch algorithms:
Please visit the main DataSketches website for more information.
If you are interested in making contributions to this site, please see our Community page for how to contact us.
