Delete  redundant content of 'docs/extend/plugins.md'
Delete  redundant content of 'docs/extend/plugins.md'

Signed-off-by: Yanqiang Miao <miao.yanqiang@zte.com.cn>

Update plugins.md

Update plugins.md

allencloud/cli,thaJeztah/cli,ashfall/cli,cpuguy83/cli,docker/cli,e11137/cli,ashfall/cli,dnephin/cli,redpanda/cli,Zebrilee/cli,allencloud/cli,docker/cli,cpuguy83/cli,redpanda/cli,e11137/cli,Zebrilee/cli,dnephin/cli,thaJeztah/cli,riyazdf/cli,riyazdf/cli