Add Developer docs for logs feature

[adambkaplan]

Our DEVELOPMENT.md should be updated to include guidance on how to emulate the different log storage providers. Alternatively, we could add a separate doc that focuses on this topic.

For example:

• AWS S3 can be faked out or replaced with any S3-compliant object storage, such as minio
• GCS has emulators such as fake-gcs-server

Originally posted by @adambkaplan in #552 (review)

[adambkaplan]

/kind documentation

[tekton-robot]

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