docs: add section about in transit encryption

[sweb]

Description

Docs section about in-transit encryption options and aconfiguration

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

Author

• Changes are OpenShift compatible
• CRD changes approved
• CRD documentation for all fields, following the style guide.
• Helm chart can be installed and deployed operator works
• Integration tests passed (for non trivial changes)
• Changes need to be "offline" compatible
• Links to generated (nightly) docs added
• Release note snippet added

Reviewer

• Code contains useful comments
• Code contains useful logging statements
• (Integration-)Test cases added
• Documentation added or updated. Follows the style guide.
• Changelog updated
• Cargo.toml only contains references to git tags (not specific commits or branches)

Acceptance

• Feature Tracker has been updated
• Proper release label has been added
• Links to generated (nightly) docs added
• Release note snippet added
• Add type/deprecation label & add to the deprecation schedule
• Add type/experimental label & add to the experimental features tracker

[sbernauer]

I like the new docs! WDYT of adding the full example as an kuttl test so we notice once it breaks?

[sweb]

I like the new docs! WDYT of adding the full example as an kuttl test so we notice once it breaks?

kuttl test in e5129c4

One thing to note here: The test only "works" with the Spark entrypoint fix - because we check app status and on 26.7 images it will always succeed, so that is not informative. We can check log outputs but since the fix is already in main, I refrained from that.

[sbernauer]

Thanks!

[sbernauer]

Thanks for adding this and the test!