Makefile: clarify a comment

os user <gnusercn@gmail.com> writes:
From the last comment, arch makefile will override vmlinux. It seems
vmlinux will not be checked by `make'. But from my test, although
`all:' will be re-defined in arch Makefile (ARM arch), vmlinux will
still be checked and the commands associated will be executed. Should
we use another word instead of "overridden"?

Reported-by: os user <gnusercn@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

Makefile

@@ -526,7 +526,7 @@ endif # $(dot-config)
 # The all: target is the default when no target is given on the
 # command line.
 # This allow a user to issue only 'make' to build a kernel including modules
-# Defaults vmlinux but it is usually overridden in the arch makefile
+# Defaults to vmlinux, but the arch makefile usually adds further targets
 all: vmlinux
 
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE