Add a breaking changes warning and an explanation of legacy with main-db1.

Author: whamm86

.github/workflows/prerelease-on-merge-to-main.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - main-db1
   schedule:
     - cron: '0 23 * * 1-5' # This is 1:00 AM Berlin time from Monday to Friday
   workflow_dispatch:  # Allows manual triggering
@@ -274,6 +275,8 @@ jobs:
         run: |
           if [ "${{ github.ref }}" == "refs/heads/main" ]; then
             echo "tag=main" >> $GITHUB_OUTPUT
+          elif [ "${{ github.ref }}" == "refs/heads/main-db1" ]; then
+            echo "tag=legacy" >> $GITHUB_OUTPUT
           else
             echo "tag=develop" >> $GITHUB_OUTPUT
           fi

README.md

@@ -1,3 +1,29 @@
+## ⚠️ Important Notice: Breaking Changes in `main`
+
+The `main` branch contains **breaking changes** compared to previous versions of the system.
+
+These changes may require adjustments in existing integrations, configurations, or deployments. Please review the changes carefully before upgrading.
+
+### What This Means
+- Existing setups may no longer work without modification
+- Migration effort may be required  
+- Db Schema has changed 
+- -NET 9.0 is used now
+
+### Legacy Support
+
+If you need to continue working with the previous version, please use the dedicated legacy branch:
+
+➡️ **`main-db1`**
+
+This branch is maintained to support the older version and ensure compatibility with existing systems. Docker images for main-db1 are tagged legacy.
+
+### Recommendation
+
+- Use `main` for all **new development** and future-ready integrations  
+- Use `main-db1` only if you depend on the **legacy implementation**
+
+
 # Eclipse AASPE Server
 
 > ### Status