setup: Add new misc settings page for smaller notes.
setup: Add new misc settings page for smaller notes.

Adds documentation for:
 - /etc/modules-load.d
 - /etc/sysctl.d
 - /etc/motd.d

ksmaheshkumar/docs-2,hkjn/docs-1,skynet/docs,coreos/docs,atxwebs/docs,endocode/coreos-docs,marineam/coreos-docs,bq-xiao/docs,mischief/coreos-docs,michelleN/docs,wli6/docs,jonboulle/docs,jdloft/docs,robszumski/docs,mjg59/docs,joshix/docs,iankronquist/docs,ionave/docs