updated docs

Signed-off-by: Nwusongqing <wusongqing@huawei.com>

en/contribute/documentation-contribution.md

@@ -49,6 +49,7 @@ You can perform the following steps to modify or supplement a file:
     Signed-off-by: user.name <user.email> // Note that *user.name* and *user.email* must be the same as those used for DCO signing.
 
     ![](figures/Signed-off-by-example.png)
+![](figures/无标题2.png)
 
     The Docs team will review your edits and update the file accordingly.