To run this example you need to generate ssh key for each repository that you are planing to create and put generated public keys into repos/deployKey folder. Also please name each key same as repository. For more about key generation please visit this link
Next step you need to create file for input variables with *.tfvars extension The content of this file should be something like this:
github_token = <GITHUB TOKEN> # https://help.github.com/articles/creating-a-personal-access-token-for-the-command-line/
organization_name = "<NAME OF ORGANISATION>"
repositories = ["repository name", "repository name"]