A bit more documentation for migration towards new setup

Following discussion with @mlbonhomme yesterday

requested review from @erouchet

assigned to @babadie

added 3 commits

• ddfeb01a - 1 commit from branch master
• 1f536e8e - Clean docker containers
• 040f97fa - A bit more doc for devs

Compare with previous version

added 3 commits

• 2f91bfe3 - 1 commit from branch master
• e4c50fac - Clean docker containers
• 33b236d7 - A bit more doc for devs

Compare with previous version

resolved all threads

added 6 commits

• 33b236d7...4632b510 - 3 commits from branch master
• 38ddc914 - Clean docker containers
• 2915dda3 - A bit more doc for devs
• 40a34b30 - Do not run clean-docker

Compare with previous version

Please have a look again @erouchet

added 5 commits

• 40a34b30...93500257 - 2 commits from branch master
• b95d1402 - Clean docker containers
• 2c908416 - A bit more doc for devs
• fc3bb0d7 - Do not run clean-docker

Compare with previous version

enabled an automatic merge when the pipeline for fc3bb0d7 succeeds

merged