docs/zh_CN: Add new translation of admin-guide/bootconfig.rst

The last English version used:
  commit 2f51efc6

 ("docs: bootconfig: Add how to embed the
  bootconfig into kernel")

Signed-off-by: Wu XiangCheng <bobwxc@email.cn>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/386249dc333a3e40b80c3a9483d60d2bfd24a6c4.1663850554.git.bobwxc@email.cn
Signed-off-by: Jonathan Corbet <corbet@lwn.net>