[PATCH] doc: update help message

[Bin Meng]

On Thu, Jan 14, 2021 at 7:04 PM Patrick Delaunay
<patrick.delaunay at foss.st.com> wrote:
>
> Update the help message used for 'make help':
>
>   Documentation targets:
>     Linux kernel internal documentation in different formats from ReST:
> =>
>     U-Boot documentation in different formats from ReST:
>
> Signed-off-by: Patrick Delaunay <patrick.delaunay at foss.st.com>
> ---
>
>  doc/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>