This pulls a list of files with the .gitattributes extension (FOO.gitattributes)
and builds a list to prompt you to pick the file you want. If Common.gitattributes is
found, you will also be asked if you want to include them.
CLI
-source: Specify the source repository
-stdout: Write to STDOUT instead of ./.gitattributes
Configuration
The configuration values can be set with gh config set KEY.
gh_gitattributes_source: The default source repository to use