docs/zh_CN: Fix two missing labels in zh_CN/process

* Add back still referenced labels in submitting-patches.rst and
  email-clients.rst.
* Fix a typo.

Fixes: fdb34b18b959 ("docs/zh_CN: Update zh_CN/process/submitting-patches.rst to 5.19")
Fixes: d7aeaebb920f ("docs/zh_CN: Update zh_CN/process/email-clients.rst to 5.19")
Signed-off-by: Wu XiangCheng <bobwxc@email.cn>
Link: https://lore.kernel.org/r/Yv7i1tYMvK9J/NHj@bobwxc.mipc


Signed-off-by: Jonathan Corbet <corbet@lwn.net>