add doc changes for DurableState deleteObject

[pjfanning]

In pekko 1.1, we are encouraging libs to have a failed future if deleteObject(persistenceId, revision) doesn't delete rows.

https://github.com/apache/pekko/pull/1271

[pjfanning]

@kerr @Roiocam @nvollmar the only mention in our existing docs for DurableState persistence about deletes is

https://pekko.apache.org/docs/pekko/current/typed/durable-state/persistence.html#effects-and-side-effects

I don't know much about Pekko Persistence but this does not appear to relate to the use of the 'deleteObject' API. See https://github.com/apache/pekko/pull/1271. I don't feel especially well qualified to describe the JdbcDurableStateStore API.

Maybe it is enough to just release note the change in #1271 and rely on the Javadoc/Scaladoc for the JdbcDurableStateStore API.

[Roiocam]

I will say it is not the user API, so we don't have to update the documents related to Persistence.

we can update the plugin documents in the https://pekko.apache.org/docs/pekko/current/persistence-journals.html. but it also does not contain durable store.

[He-Pin]

We can only update the how to implement a persistent plug-in part.