Etiquette for answering your own question
It just happened that my question didn't exist anymore (I found the answer) while writing it:
git website update strategy - how to sync dev and live repositories?
But I found the content so valuable that I posted it anyway.
Surely, it will add value to stackoverflow and other trying to resolve the same problem.
But, sadly, there was no question in the "question" anymore.
What should I have done? I don't have another proper place to publish that content...