Add doc for not supported operations for credential vending

[MonkeyCanCode]

Description

This is for adding doc around which operations are not supported by credential vending.

Fixes # (390)

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• Documentation update
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

Please delete options that are not relevant.

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• If adding new functionality, I have discussed my implementation with the community using the linked GitHub issue

[eric-maynard]

Should we be using the new Hugo-style links? I am honestly not clear on that

[jbonofre]

@eric-maynard is right, I think it's better to use Hugo style link to have a clean documentation.

[MonkeyCanCode]

Thanks for the info. Will finish validations later today then update the PR with suggestions above.

[MonkeyCanCode]

From some quick read, Hugo style link is mainly for internal links within the site and external links seems to be preferred as markdown's style instead. Also, there are many places we are using markdown style links for external reference across current site. If that is more preferred, should we do it in a different PR instead?

Then in terms of table maintenance operations validation with credential vending, following are tested:

Trino:

• optimize: passed
• expire_snapshots: passed
• remove_orphan_files: passed
• drop_extended_stats: passed

Spark:

• expire_snapshots: passed
• remove_orphan_files: failed (not supported as mentioned in this PR)
• rewrite_data_files: passed
• rewrite_manifests: passed
• rewrite_position_delete_files: passed

[flyrain]

@MonkeyCanCode thanks a lot for validating maintenance procedures. It's a good callout, but it is essentially an Spark issue. Maybe we can reword to something like this:

- **remove_orphan_files:** Apache Spark can't use credential vending for this due to a known issue. See [apache/iceberg#7914](https://github.com/apache/iceberg/pull/7914) for details. 

[MonkeyCanCode]

Anytime. Updated.