Fixed description and keywords on Ubuntu installation docs

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
command line nit
Merge pull request #5886 from financeCoding/mac_doc_nit

command line nit
Merge pull request #5882 from jamtur01/ubfix

Fixed description and keywords on Ubuntu installation docs
Check uid ranges

Fixes #5647
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)