buildsystem: add more options

Signed-off-by: Andrew 'Necromant' Andrianov <andrew@ncrmnt.org>
doc: update ARCHMATRIX

Signed-off-by: Andrew 'Necromant' Andrianov <andrew@ncrmnt.org>
doc: update READMEs

Signed-off-by: Andrew 'Necromant' Andrianov <andrew@ncrmnt.org>