I want add README.md file for in will be visible and editable in NetBeans 8.2 in Maven Java project type, But when the file lies in th project root it still unvisible in the IDE...
Interestingly enough there is a plugin for it. See at github or at netbeans portal To install it go to Tools -> plugins -> Available Plugins and search for readme. Choose plugin called Display readme files in project view. You can change which files to show on the Tools -> options -> Miscellaneous->Display more files panel:
UPDATE 2022:
Currently, the old NetBeans portal unavailable because it was decommissioned. You can download plugin from here and install manually. To install it manually, download the file readmeinprojectview-1.6.0.nbm then go to Tools -> Plugins -> Donwloaded -> Add Plugins. Then select the plugin and click Install.