forked from Mirrors/opensbi

At present in the rendered platform guide, all instances of <xyz> are missing. Use < and > to replace <> to make them visible. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Xiang W <wxjstz@126.com> Reviewed-by: Anup Patel <anup.patel@wdc.com>