Thanks for your reply Bartosz.

I can see that the PHP based skins are working now (Mediawiki 1.35.*) but the same skin does not work on Mediawiki 1.36+.

I mentioned in my previous email that I built a skin long ago and  Jon Robson helped to upgrade that afterwards.

My concern is that Mediawiki is moving towards Mustache and old skin docs are marked as outdated. But I found only one single page doc about this new system. Though you are saying those are valid.

The core team who are working on this skin section can create the equivalent amount of docs which are available for PHP based skins. I can help to write the docs as well but as I am not building the system I have a number of queries regarding this. If I get the answers then I can create the related docs.

Is there anyone who can help me to improve the skin docs of MediaWiki and I will get the help to build the skin from that.