docs(0004): BREAKING remove cancellationCondition

what was previously known as Universal mode has been incorporated into the core Interledger Protocol. the Atomic mode is being removed from the core protocol and will be used via extensions to the protocol.
based on #28

0004-ledger-plugin-interface/0004-ledger-plugin-interface.md

@@ -308,9 +308,8 @@ fields can be left undefined (but not any other false-y value) if unused.
 | `String` | [amount](#amount) | Decimal transfer amount |
 | `Buffer` | [data](#data) | Data packet or memo to be sent with the transfer, starts with an ILP header |
 | `Buffer` | [noteToSelf](#notetoself) | Host-provided memo that should be stored with the transfer |
-| `String` | [executionCondition](#executioncondition) | Cryptographic hold condition, used in [UTP](../0006-universal-transport-protocol/)/[ATP](../0007-atomic-transport-protocol/) |
-| `String` | [cancellationCondition](#cancellationcondition) | Cryptographic abort condition, used in [ATP](../0007-atomic-transport-protocol/) |
-| `String` | [expiresAt](#expiresat) | Expiry time of the cryptographic hold, used in [UTP](../0006-universal-transport-protocol/) |
+| `String` | [executionCondition](#executioncondition) | Cryptographic hold condition |
+| `String` | [expiresAt](#expiresat) | Expiry time of the cryptographic hold |
 | `Object` | [custom](#custom) | Object containing ledger plugin specific options |
 
 
@@ -376,15 +375,6 @@ Ledger plugins that do not support holds MUST throw an `HoldsNotSupportedError`
 
 Ledger plugins that do support holds, but do not support the given condition type or bitmask MUST throw a  `ExecutionConditionNotSupportedError`.
 
-#### cancellationCondition
-<code>**cancellationCondition**:String</code>
-
-A [cryptographic condition](../0002-crypto-conditions/) used for implementing holds. If this condition is met and the transfer is on hold, the ledger MUST cancel the transfer and return the funds to the sender.
-
-Ledger plugins that do not support holds or do not support cancellation MUST throw a `CancellationNotSupportedError` if this parameter is provided.
-
-Ledger plugins that do support cancellation, but do not support the given condition type or bitmask MUST throw a `CancellationConditionNotSupportedError`.
-
 #### expiresAt
 <code>**expiresAt**:String</code>