feat: add migration guide for operation mode

[isamu-takagi]

Description

Add migration guide for operation mode.

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[github-actions]

Documentation URL: https://tier4.github.io/autoware-documentation/pr-46/
Modified URLs:

• https://tier4.github.io/autoware-documentation/pr-46/design/autoware-interfaces/prototyping/
• https://tier4.github.io/autoware-documentation/pr-46/design/autoware-interfaces/prototyping/migration/operation-mode/

[messi49]

内容は良いと思います。
もしTIER IV APIが今後なくなる/見直されるのであれば "Deprecated" みたいな説明はいれておいて頂けると助かります！

[isamu-takagi]

もしTIER IV APIが今後なくなる/見直されるのであれば "Deprecated" みたいな説明はいれておいて頂けると助かります！

@messi49 上の階層のページで deprecated にカテゴライズされています。
https://tier4.github.io/autoware-documentation/tier4-main/design/autoware-interfaces/prototyping/