for 20.04 Ubuntu serverguide changing URL and markdown language

[mahesh]

As of the 20.04 cycle, the Ubuntu serverguide is changing from DocBook to discourse markdown (markup?) language.
A link will be added shortly to the main landing page at help.ubuntu.com, but meanwhile here is a direct link: https://ubuntu.com/server/docs. Every web page has a link to the discourse source page at the bottom, where users can make suggestions, point out errors, and (if you have rights) fix bugs on pages.