!1785 README: Remove out-of-date contribution guide

Merge Pull Request from: @ci-robot 
 
PR sync from: Wei Li <liwei391@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/7CEZ6NYTS3GYYHEHIRSCXMVPIZ7PKNB4/ 
 
https://gitee.com/openeuler/kernel/issues/I7THI2 
 
Link:https://gitee.com/openeuler/kernel/pulls/1785

 

Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>