That is what the documentation you are referring to mentions.

Set up access to multiple repositories
To create an SSH key for each of your repositories, follow the steps outlined above.
After you have added the keys to the remote repositories, create a local ~/.ssh/config file to alias each of the keys to their corresponding repository names.

For example, if you have two repos configured on GitHub, testing and testing2, and both your cPanel and GitHub usernames are cptest, create or modify the ~/.ssh/config file with these contents:

Host testing.github.com

       Hostname github.com

       IdentityFile /home/cptest/.ssh/testing

       User git



Host testing2.github.com

       Hostname github.com

       IdentityFile /home/cptest/.ssh/testing2

       User git

Compared to their documentation, I would use:

IdentityFile /home/cptest/... (instead of IdentityFile=...)
User git
a FQDN-like Host entry: xxx.yyy.com
That way, the URL becomes: git clone testing.github.com:me/myRepo

If the cPanel requires a valid protocol, use:

ssh://github.com-testing/me/myRepo

^^^^^^                 ^^^

(valid protocol)       (/, not 

In your case:

ssh://top25vineyards.github.com/me/myRepo

ssh://top25vineyards.github.com/Penk13/top25vineyards

(to mimic an fully-qualified domain name)