images/README: remove bullets from recipe entries
images/README: remove bullets from recipe entries

Since we removed the hierarchy structure from the images README, the
bullets (*) no longer have meaning in the README.

Remove them for clarity.

Signed-off-by: Alex Stewart <04cdb2793e4fb0120cc30d1c823099f3862701f4@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt