Update getting_started.md
Update getting_started.md

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AcalephStorage/coreos-ipxe-server,joao-parana/coreos-ipxe-server,BongaD/coreos-ipxe-server,kelseyhightower/coreos-ipxe-server,AcalephStorage/coreos-ipxe-server,joao-parana/coreos-ipxe-server,andrewrothstein/coreos-ipxe-server,andrewrothstein/coreos-ipxe-server,kelseyhightower/coreos-ipxe-server,BongaD/coreos-ipxe-server