User Info Fetcher: Document data differences between backends, and/or how to query it manually

Currently, we only document the Keycloak "format" (username is the keycloak username, groups are "file-system-style paths"), but not the AD one (username is the Kerberos UPN, groups are distinguished names), or how it might differ between them (beyond a slight mention that there is a difference).

We should give examples for each, and/or give an easy example for how to query it yourself to see the data format that applies to your environment.

issue にリンクされている User Info Fetcher API セクションから始め、既存の Keycloak の説明を確認してください。対応する AD データ形式を文書化し、両方のバックエンドの例を含め、ユーザーが自分の環境で形式を特定できるように、データを手動でクエリする方法を説明してください。