Add additional information about the abignore file.

Replace the entire text with just the following.

# .abignore lets you configure which of your files and folders should be excluded from your application package during the build process with the AppBuilder command-line interface. Each project created with AppBuilder 2.6 or later contains a default .abignore which lists a number of system files and folders that might affect the size of your app or might prevent build operations from completing successfully. 
#
# For more information about .abignore and how to write exclude and include rules for your projects, see http://docs.telerik.com/platform/appbuilder/testing-your-app/abignore