I would suggest Make changes inside the docker container which you run using docker run command by 

docker exec -ti --user root odoo_container_id /bin/bash

this command will let you make changes in the container, from that container you can create your own docker image and upload it to docker hub: more details here

Or, in case your making too many changes in the image, then you should map/mount[volumes] the source code directory of docker container to the any external location, more details here