Add a README file for the bundler (#5526)
Add a README file for the bundler (#5526)

Add a README file for the bundler

Add a readme file that explains why the Bundler is in the core-setup repo, 
and why it is built as a command line tool.

wtgodbe/core-setup,MichaelSimons/core-setup,MichaelSimons/core-setup,crummel/dotnet_core-setup,crummel/dotnet_core-setup,crummel/dotnet_core-setup,wtgodbe/core-setup,MichaelSimons/core-setup,crummel/dotnet_core-setup,MichaelSimons/core-setup,wtgodbe/core-setup,MichaelSimons/core-setup,crummel/dotnet_core-setup,crummel/dotnet_core-setup,wtgodbe/core-setup,wtgodbe/core-setup,wtgodbe/core-setup,MichaelSimons/core-setup