complete getting started tutorial with screen

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
Merge branch 'devel' of github.com:ULHPC/tutorials into devel

# By Hyacinthe Cartiaux
# Via Hyacinthe Cartiaux
* 'devel' of github.com:ULHPC/tutorials:
  Sequential, readme.md: typo