docs/zh_CN: Update process index to 6.7-rc2

Update to commit f1477dbf

 ("docs: add backporting and conflict
resolution document")

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/7f79015d251b3ad88d6ea596508e39832623db9d.1700474235.git.siyanteng@loongson.cn