thank you for you help.
I do not regularly follow the mediawiki releases and did not updated the skin for a long time. So, even though I know that Release notes are the best place to look into while updating the skin. You updated one method which was deprecated in 1.36 and there might be other method calls while may deprecate on 1.37 or the next release. And structurally MediaWikiBootstrap and Example/SkinLabsSkin is different.
In summary I want to update the skin to Mustache but the skin will look similar.
If I read the Manual:Skinning Part 2 and Manual:Skinning Part 3 I would be able to built a PHP based skin. But if I want to build a Mustache based skin there is not equivalent amount of doc available.
I have a number of queries, those might look silly but as I do not building the skin system I do not have much info about those. Like I installed 1.37 and installed Example skin. After that I found that the logo is not visible, but there is a file on the LocalSettings logo path. What should i do now? How to set the Favicon? how can I show the language links? will I have to do anything for RTL language wiki? how to control the footer links? what are the steps to format the categories area? I also need to add Google Fonts, Icon fonts. how to show/hide the navigation menu items, how to format those? styling the search box, add an extra class/id with that, formatting the search box results. None of these questions have answers to that Manual:How to make a MediaWiki skin doc.
If you can answer to my queries, I also can write docs and update that single page as well.