installation of babel

[ThierryO]

add the installation of babel-english, babel-dutch and babel-french to the instructions

[ElsLommelen]

While updating tinytex and texlive after an R and RStudio update, these packages somehow disappeared (while they were on my computer before the R update). So I suggest adding this to the INBOmd readme before the R update at INBO. (Even if it is not suggested to do an update of INBOmd, some might to this if things don't work properly.)