The F10 release notes (section 188.8.131.52) says that to PXE boot to an NFS ISO installation you now need to add "method=nfsiso:server:/path" to the command line.
There are several problems with this:
(a) method= is apparently deprecated in favour of rep0=
(b) adding it doesn't seem to achieve anything as I am still prompted
for a source and choosing an NFS install still works
On top of that the actual information which would be useful is that you now have to extract install.img from the ISO and place it in an images directory alongside the ISO on your NFS server.
Change commited. Thanks for the report.