docs: update admin credentials locations

docs/installation/post-installation.md

@@ -15,12 +15,16 @@ Save the following files to a safe location like a password manager (if you're u
 - ArgoCD:
     - Username: `admin`
     - Password: run `./scripts/argocd-admin-password`
-- Grafana:
-    - Username: `admin`
-    - Password: `prom-operator` (TODO: use random password)
 - Gitea:
     - Username: `gitea_admin`
     - Password: get from `global-secrets` namespace
+- Kanidm:
+    - Usernames: `admin` and `idm_admin`
+    - Password: run `./scripts/kanidm-reset-password admin` and `./scripts/kanidm-reset-password idm_admin`
+- Jellyfin and other applications in the \*arr stack: see the [dedicated guide for media management](../how-to-guides/media-management.md)
+- Other apps:
+    - Username: `admin`
+    - Password: get from `global-secrets` namespace
 
 ## Run the full test suite