Adding documents

[Mohammad Islam]

Hi Sandeep,Continuation of our discussion from KNOX-861, about how to document 
new feature in Knox.I'm not sure which file to update.For example, I would like 
to add a section in dev guide.I need some clarifications:what file need to be 
updated? I can see multiple dev-guide.html for each version.Should I change it 
in html format?I can see book.md file too.
Regards,Mohammad