keystonerc is a file that's used for exporting keystone credentials to environment variables so that you wouldn't have to pass it everytime when you use keystone. Create it wherever you wish to create it. Just create it on your home folder

$ vi ~/keystonerc

write the following content into the keystonerc file.

export ADMIN_TOKEN=(your_admin_token)
export OS_USERNAME=(your_admin_username)
export OS_TENANT_NAME=(your_admin_username)
export OS_PASSWORD=(your_admin_password)
export OS_AUTH_URL=http://(ip_address_of_keystone):5000/v2.0

and then just execute that file with

$ cd ~/
$ . ./keystonerc

Now when you do this, all these are stored in your environment variables (env). You can simply run commands without specifying any credentials. Try

keystone service-list

The drawback of this approach is, the exported environment variable will be visible only to that terminal where you ran keystonerc. To make it available across all the terminals, add those exports to .bashrc, if Ubuntu is your distro, else to .bash_profile.

If you are looking for a multi-region environment, you should visit this IBM link for more details.

Hope this was what you were expecting.