docs: add missing InvenioRDM application.properties entries to v1.14.0 migration

docs/migrations/released/v1.14.0.md

@@ -34,6 +34,55 @@ Before applying any migrations:
 
 ---
 
+## Application properties changes
+
+InvenioRDM external service integration requires new configuration entries in
+`application.properties`. Operators upgrading from v1.13.0 **must** add these
+properties — without them the application will fail to start (the
+`InvenioRdmInstance` list is mandatory).
+
+### New properties
+
+| Property | Type | Description |
+|---|---|---|
+| `qbic.external-service.invenio-rdm.instances[N].id` | String | Stable identifier for the InvenioRDM instance (e.g. `zenodo`, `fdat`). Used as a lookup key in the UI. |
+| `qbic.external-service.invenio-rdm.instances[N].display-name` | String | Human-readable name shown in the UI (e.g. `Zenodo`, `FDAT`). |
+| `qbic.external-service.invenio-rdm.instances[N].base-url` | URL | Base URL of the InvenioRDM instance API (e.g. `https://zenodo.org`). |
+| `qbic.external-service.invenio-rdm.instances[N].api-version` | Integer | Invenio REST API version for per-instance adapter dispatch (currently unused; defaults to version 12). |
+
+### Default configuration
+
+The default `application.properties` ships with two pre-configured instances:
+
+```properties
+# ── InvenioRDM instances ────────────────────────────────────────
+qbic.external-service.invenio-rdm.instances[0].id=zenodo
+qbic.external-service.invenio-rdm.instances[0].display-name=Zenodo
+qbic.external-service.invenio-rdm.instances[0].base-url=https://zenodo.org
+qbic.external-service.invenio-rdm.instances[0].api-version=12
+
+qbic.external-service.invenio-rdm.instances[1].id=fdat
+qbic.external-service.invenio-rdm.instances[1].display-name=FDAT
+qbic.external-service.invenio-rdm.instances[1].base-url=https://fdat.uni-tuebingen.de
+qbic.external-service.invenio-rdm.instances[1].api-version=12
+```
+
+> **Note:** The `instances` list uses zero-based indexed keys. To add a third instance, use
+> `instances[2].<property>`. Removing an instance means removing its entries from the
+> configuration — the application will stop offering the ability to connect datasets from
+> that instance.
+
+### Operator action
+
+1. **Review** the properties above and adjust them for your environment. In particular:
+   - Verify `base-url` values point to the correct InvenioRDM instances for your organisation.
+   - Add or remove instance entries (`instances[0]`, `instances[1]`, …) as needed.
+2. **Add** the properties to your `application.properties` (or equivalent externalised
+   configuration / environment variables).
+3. **Restart** the application after applying schema migrations.
+
+---
+
 ## Summary of schema changes in this release
 
 | # | Script | Description | Risk |
@@ -323,9 +372,10 @@ mysql -u <user> -h <host> -P <port> data_management < /tmp/complete-schema-1.13.
 
 ## Post-migration checklist
 
-After applying all migrations:
+After applying all migrations and configuration changes:
 
-1. **Restart the application.**
+1. **Verify application.properties contains all new InvenioRDM instance entries** (see *Application properties changes* above).
+2. **Restart the application.**
 2. **Verify the application starts without errors** — check logs for schema
    mismatch warnings.
 3. **Run a smoke test** against a project with no connected datasets to confirm