Document Internal Topic Requirements for Outbox Feature

[bibryam]

What content needs to be created or modified?
The Outbox feature relies on an internal message topic. With some messaging providers, depending on the permissions, this topic cannot be auto-created by Dapr and needs to be manually created by a user.
It is not clear what is the name (and other parameters such as partitions for example) that are needed for this topic.

Describe the solution you'd like
I'd like to see the internal topic requirements, and the naming convention used to generate this topic documented.

Where should the new material be placed?
Outbox doc