arch.md: edit to systemd setup
freebsd.md: re-jigged order & portmaster use

Added command for installing ports with portmaster
Re-order text to reflect order when installing from scratch
freebsd.md: edits to bash instructions and fix typos.
arch.md: add git config and extra packages

* add git autocorrect option
* edited list of packages to install
freebsd.md: added bash completion port to portmaster list