Handle main/dev automatically

[guimou]

Main and Dev branches are mentioned literally in different files, making merging to main more difficult. We need to find a way to handle this. The files are:

• bootstrap/applicationset/applicationset-bootstrap.yaml -> Definition of the ApplicationSet
• bootstrap/bootstrap.md -> Bootstrap documentation
• content/antora.yml -> instructions compilation
• content/modules/ROOT/pages/05-03-web-app-deploy-application.adoc -> instructions for app deployment
• lab-materials/05/05-05/process_claims.yaml -> claim processing script
• bootstrap/ic-user-projects/create-projects-and-resources-job.yaml -> project cloning from GH

Preferably, the solution must be applicable to all those files.