Documentation: kbuild: Remove obsolete include/asm symlink step

As of commit f7f16b7799ed68654850ab340ef812895aebcf4c ("kbuild: drop
include/asm"), the include/asm symlink is no longer created.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>

Documentation/kbuild/makefiles.txt

@@ -818,17 +818,16 @@ a few targets.
 When kbuild executes, the following steps are followed (roughly):
 1) Configuration of the kernel => produce .config
 2) Store kernel version in include/linux/version.h
-3) Symlink include/asm to include/asm-$(ARCH)
-4) Updating all other prerequisites to the target prepare:
+3) Updating all other prerequisites to the target prepare:
    - Additional prerequisites are specified in arch/$(ARCH)/Makefile
-5) Recursively descend down in all directories listed in
+4) Recursively descend down in all directories listed in
    init-* core* drivers-* net-* libs-* and build all targets.
    - The values of the above variables are expanded in arch/$(ARCH)/Makefile.
-6) All object files are then linked and the resulting file vmlinux is
+5) All object files are then linked and the resulting file vmlinux is
    located at the root of the obj tree.
    The very first objects linked are listed in head-y, assigned by
    arch/$(ARCH)/Makefile.
-7) Finally, the architecture-specific part does any required post processing
+6) Finally, the architecture-specific part does any required post processing
    and builds the final bootimage.
    - This includes building boot records
    - Preparing initrd images and the like