Documentation/early-userspace/README fix a typo

Corrected the swapped characters in the word arugemnt to argument.
Signed-off-by: Stefan Huber <steffhip@googlemail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Documentation/early-userspace/README

@@ -71,7 +71,7 @@ can really be interpreted as any legal argument to
 gen_initramfs_list.sh.  If a directory is specified as an argument then
 the contents are scanned, uid/gid translation is performed, and
 usr/gen_init_cpio file directives are output.  If a directory is
-specified as an arugemnt to scripts/gen_initramfs_list.sh then the
+specified as an argument to scripts/gen_initramfs_list.sh then the
 contents of the file are simply copied to the output.  All of the output
 directives from directory scanning and file contents copying are
 processed by usr/gen_init_cpio.