docs: fix file's permissions
docs: fix file's permissions

The README.md and the *.png should not have the executable
permissions, remove them.

Signed-off-by: Lai Jiangshan <b337eedf453972390e4695e362aeea2634ef4e0c@gmail.com>

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