Install notes for non-raspian

[easytarget]

eg: fedora:
dnf install python3 python3-devel python3-pip rrdtool rrdtool-devel

• install to /usr/local/share/ to avoid selinux issues and adjust jsername too..

[easytarget]

get rid of the inline sudos, move to machine prep section.
clarify GPIO stuff only for PI systems at present

[easytarget]

remove version outputs; add a 'minimum' note (3.7)