beginner trouble with github pages publishing for '/docs' subfolder of repo

[Urs Rau]

Thanks for this great tool, 

What are the correct values to enter into the _config.yml file for 'url:' and 'root:' if one wants to publish the github pages from the '/docs' subfolder of the repo?

url: http://my-gh-acc-name.github.io/my-tld-dom-site

root: /my-tld-dom-site/

or 

url: http://my-gh-acc-name.github.io/my-tld-dom-site/docs

root: /my-tld-dom-site/docs/

Also is there a way to add the required CNAME file to the hexo data so it uploads that file into the publish root under '/docs/CNAME'?