proc.5: Clarify that boot arguments can be embedded in image

proc.5: Clarify that boot arguments can be embedded in image

With the advent of the CONFIG_BOOT_CONFIG Kconfig option, kernel boot
arguments can now be embedded in the kernel image, either attached
to the end of initramfs or embedded in the kernel itself.  Document
this possibility in the /proc/cmdline entry of proc.5.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>