[RELEASE] Operator v5.0.7 doc updates

[djwfyi]

Operator v5.0.7 has changes that impact the docs:

• kubectl minio tenant info now includes tenant secret info (PR #1704)
• Can now mount volumes to the Operator pod (PR #1700)
• Add SFTP support during tenant creation (PR #1685 and PR #1692) (Existing Tenants also)
• kubectl minio delete now has a --force flag (PR #1687)

Helm changes:

• Support digest for OpenShift PR #1706
• The helm chart has been split into separate files as per best practices PR #1677

[feorlen]

minio/operator#1677 doesn't require doc updates at this time.

Specifics of chart structure/contents will get covered in a future section about how to customize. For now we link to the relevant Helm docs and presume anyone needing this level of customization already knows how charts work.

[feorlen]

Similar to previous, no doc updates needed for minio/operator#1706

The new option is documented with a comment in operator/values.yaml.

[djwfyi]

Last item relates to Helm charts, which are not documented.
Also waiting for feedback on the PR 1700 about the use case.

[feorlen]

Requested use case details for minio/operator#1700. We are unclear about their intended purpose that needed this functionality.