Improve documentation of iso-scan/filename feature

From the current man page it's really hard to tell what will be output of this command.
4 years ago · cb495a073e
1 changed files with 3 additions and 0 deletions
--- a/dracut.cmdline.7.asc
+++ b/dracut.cmdline.7.asc
@ -113,6 +113,9 @@ resume=UUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
				@@ -113,6 +113,9 @@ resume=UUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
 iso-scan/filename
 ~~~~~~~~~~~~~~~~~

+Mount all mountable devices and search for ISO pointed by the argument. When
+the ISO is found set it up as a loop device. Device containing this ISO
+image will stay mounted at /run/initramfs/isoscandev.
 Using iso-scan/filename with a Fedora/Red Hat/CentOS Live iso should just work
 by copying the original kernel cmdline parameters.