Add a link PlayWithDocker (or similar)

[Gustry]

Because it's nice to try quickly on a remote server : https://labs.play-with-docker.com/

Similar to https://github.com/opengisch/docker-lizmap/blob/3.7/README.md at the top of the readme.

We can give a stack parameter :

http://play-with-docker.com/?stack=https://raw.githubusercontent.com/jancelin/docker-lizmap/master/docker-compose.yml It's pretty awesome to have a Lizmap in a few seconds on a remote server.

I tried with the docker-compose from 3Liz, but I guess because of default env variables in the docker-compose.yml, it doesn't load.

I think @nboisteault got a previous link before ?

Then, we still need to push QGS files somehow...

[nboisteault]

I tried Gitpod one year ago and it was very easy to launch a Lizmap for testing : https://www.gitpod.io/