To place a local folder in a Docker Container on Windows 10 to mount, you can either use Docker for Windows or if you are using the Windows 10 Home Edition used, one is forced, This by hand with Virtual Box Do.
To do this, you have to use the Docker default Select Box in Virtual Box:
Then you have to restart the docker-machine in the Docker Toolbox, this will restart the docker default Virtual Box:
Now you can mount your directory in his docker-compose.yml:
volumes: - /htdocs/my_project:/var/www/html/
Now the folder in the Docker container is successfully mounted.
The following command can be used to test, whether the mount was successful:
docker exec -it CONTAINER_ID ls -ll /var/www/html