[NTG-context] missing --delete flags in mtx-update.lua

Hello, When running first-setup.sh, some of the rsync commands are missing the --delete flag: /opt/context/tex/texmf-context: ok /opt/context/tex/texmf-linux-64: no --delete flag /opt/context/tex/texmf: ok /opt/context/tex/texmf-modules: no --delete flag -- Peter