docs/zh_CN: Add zh_CN/admin-guide/sysrq.rst

Add translation zh_CN/admin-guide/sysrq.rst and link it to
zh_CN/admin-guide/index.rst while clean its todo entry.
Signed-off-by: Junhua Huang <huang.junhua@zte.com.cn>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/20210910022531.243882-1-junhuahuangdream@163.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/translations/zh_CN/admin-guide/index.rst

@@ -67,6 +67,7 @@ Todolist:
    cpu-load
    lockup-watchdogs
    unicode
+   sysrq
 
 Todolist:
 
@@ -118,7 +119,6 @@ Todolist:
    rtc
    serial-console
    svga
-   sysrq
    thunderbolt
    ufs
    vga-softcursor