[Np 1888] document file reference (#4755)
[Np 1888] document file reference (#4755)

* fix indentation

* remove debugg changes
foam-framework/foam2,foam-framework/foam2,jacksonic/vjlofvhjfgm,foam-framework/foam2,foam-framework/foam2,jacksonic/vjlofvhjfgm,jacksonic/vjlofvhjfgm,foam-framework/foam2