While the MIGRATION.md is vital, we need an automatic way of transforming the appsettings.json.

Rationale

Major version can have new entries, that might be mandatory. Therefore we need a way of telling folks that there is something new.

Another usecase is that we move entries from a section inside the appsettings.json (more likely the appsettings.dev.json and friends as the appsettings.json itself is version-controlled) to another one. The current way of dealing with it, is via the MIGRATION.md and folks have to do it manually.

Solution

Ideally, we have a companion tool (inside the tools) folder that does that. For example Nx or Angular allow also automatic migrations of files. nx migrate - we would have a similar tool.
If completely new entries were made, we should inform people what they have to do, maybe with a link to the docs. But that should be part of the migration.

Technical Requirements

• Documentation is a must. We have to guide folks through the process under the docs/ folder
• We need a new marker inside the appsettings.*.json to set the current version. Having a log of entries might not be ideal and just adds bloat.
• The console should have colorful output to make warnings or errors obvious. Especially if we have new entries where people have to provide new values.
• Backup all files before, so we can restore them in the worst case