[U-Boot] [RFC PATCH 8/9] doc: Add board to Sphinx TOC tree

[Heinrich Schuchardt]

On 7/16/19 6:42 PM, Bin Meng wrote:
> Add index.rst for board. More docs will be added later.
>
> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>

Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>