Updated .env templates with comments to mention values which cannot be changed after Docker build
This simply adds comments to the .env templates, satisfying https://gitlab.ruhr-uni-bochum.de/FDM/rdm-system/antleaf-projectmanagement/-/issues/386
This simply adds comments to the .env templates, satisfying https://gitlab.ruhr-uni-bochum.de/FDM/rdm-system/antleaf-projectmanagement/-/issues/386