Remove tx-output from API docs

docs/core-concepts/behavior.md

@@ -19,7 +19,6 @@ Not pictured is the `CommandFailed` output, which is implicit emitted whenever a
 There are some options for API clients to control the server outputs. Server outputs are controlled using the following query parameters:
 
 + `history=no` -> Prevents historical outputs display. All server outputs are recorded and when a client re-connects these outputs are replayed unless `history=no` query param is used.
-+ `tx-output=cbor` -> Outputs transaction fields encoded as CBOR instead of default JSON.
 + `snapshot-utxo=no` -> In case of a `SnapshotConfirmed` message the `utxo` field in the inner `Snapshot` will be omitted.
 
 ## Replay of past server outputs
@@ -28,4 +27,4 @@ When a `hydra-node` restarts, by default it will load its history from persisten
 
 Clients can optionally decide to skip history outputs and receive only the `Greetings` and following ones. In order to do that they can use query param `history=no`.
 
-For example if the client wants to connect to a local `hydra-node` and doesn't want to view the server history but also wants to have the transactions encoded as CBOR (base16) and prevent utxo display in `SnapshotConfirmed` messages, they would connect using default port `4001` and the full path `ws://localhost:4001/?history=no&tx-output=cbor`.
+For example if the client wants to connect to a local `hydra-node` and doesn't want to view the server history but also wants to have the transactions encoded as CBOR (base16) and prevent utxo display in `SnapshotConfirmed` messages, they would connect using default port `4001` and the full path `ws://localhost:4001/?history=no`.