Update instructions for enabling NRI. Remove the now
unnecessary step of creating an NRI configuration file.
Add a note about the shared default NRI socket path
preventing two NRI-enabled runtimes to be run with the
default configuration on a single node.
Remove a leftover/half sentence that slipped through in
an earlier commit.
Signed-off-by: Krisztian Litkey <krisztian.litkey@intel.com>
