Fix typo in documentation regarding changing inbox to outbox

[dimabarbul]

The text below suggests that path in response has changed from /inbox/... to /outbox/... But the example JSON does not shows this change.

[thjaeckle]

In fact, this change from inbox to outbox is not required, it is more of a relict of wrong documentation - I think the example once had this change to outbox also contained.

I am wondering if it would make more sense to delete this hint about changing "inbox" to "outbox". It does not really make things clearer - instead more confusing.

• a message response is already identified by the use of status in the payload
• it is correlated via the correlation-id header
• no permissions are checked - knowing the correlation-id is sufficient to answer to a message

[thjaeckle]

I would rather remove the sentence:

Notice, that the `path` of the Message has changed from *inbox* to *outbox*, 
which means the Message was sent *from* the Thing.

[thjaeckle]

LGTM, thanks 👍