docs: add Transaction example

[jdockerty]

Which issue does this PR close?

N/A, although I can link this to the Write support epic is that is useful?

What changes are included in this PR?

Adding additional documentation to the transaction module to provide a basic example of the FastAppendAction usage.

Other actions are not included at this time.

it looks like this

Are these changes tested?

N/A

[CTTY]

Hi @jdockerty , thanks for this PR! I do think adding more documentation is necessary since iceberg-rs's tx semantics is slightly different from iceberg-java. There is an ongoing effort of standardlizing transaction api and will change the existing usages a little bit, maybe we can wait until that work is finished and add the new doc later:

• feat(transaction): Add TransactionAction and related classes #1420
• feat(transaction): Implement TransactionAction for updata_loc, update_props, and upgrade_format #1433

[jdockerty]

@CTTY This sounds reasonable to me, thanks for the heads up 💯

For my understanding, the linked PRs are fundamentally changing the Transaction usage and splitting things up?

E.g. there are more well-defined actions on the new path, such as an UpdateLocationAction.

It doesn't look like this affects the FastAppendAction, which is what this doc PR adds an example for. Is this code path changing soon in a follow-up, after the other PRs have been merged?

[CTTY]

It doesn't look like this affects the FastAppendAction, which is what this doc PR adds an example for. Is this code path changing soon in a follow-up, after the other PRs have been merged?

Yes, the ongoing refactoring effort is for all transaction actions. I'm planning to work on FastAppendAction next and hopefully it will get in by next weekend