add sign func about order/contract for js/dart sdk (#14)

Author: zksemi

developer/sdk/dart/transactions/5-order-matching.md

@@ -44,6 +44,22 @@ Order(
 )
 ```
 
+### func sign
+
+```dart
+void sign(ZkLinkSigner zkLinkSigner)
+```
+
+Sign order with given [ZkLinkSigner](../signer.md#type-zklinksigner)
+
+### func toJson
+
+```dart
+String toJson()
+```
+
+Get the json str of [Order](#type-order)
+
 ## type OrderMatching
 [OrderMatching](../../../api-and-sdk/data-types/transaction/order\_matching.md) transaction type.
 

developer/sdk/dart/transactions/6-contract-matching.md

@@ -43,6 +43,22 @@ Contract(
 )
 ```
 
+### func sign
+
+```dart
+void sign(ZkLinkSigner zkLinkSigner)
+```
+
+Sign contract with given [ZkLinkSigner](../signer.md#type-zklinksigner)
+
+### func toJson
+
+```dart
+String toJson()
+```
+
+Get the json str of [Contract](#type-contract)
+
 ## type ContractMatching
 [ContractMatching](../../../api-and-sdk/data-types/transaction/contract\_matching.md) transaction type.
 

developer/sdk/js/transactions/5-order-matching.md

@@ -53,6 +53,18 @@ The [Order](../../../api-and-sdk/data-types/transaction/order\_matching.md) stru
 Order(account_id, sub_account_id, slot_id, nonce, base_token_id, quote_token_id, amount, price, is_sell, maker_fee_rate, taker_fee_rate, has_subsidy)
 ```
 
+### func sign
+
+```javascript
+/**
+* @param {ZkLinkSigner} signer
+* @returns {any}
+*/
+sign(signer)
+```
+
+Sign order with given [ZkLinkSigner](../signer.md#type-zklinksigner)
+
 ## type OrderMatchingBuilder
 
 ### constructor

developer/sdk/js/transactions/6-contract-matching.md

@@ -63,6 +63,18 @@ The [Contract](../../../api-and-sdk/data-types/transaction/contract\_matching.md
 newContract(builder)
 ```
 
+### func sign
+
+```javascript
+/**
+* @param {ZkLinkSigner} signer
+* @returns {any}
+*/
+sign(signer)
+```
+
+Sign contract with given [ZkLinkSigner](../signer.md#type-zklinksigner)
+
 ## type ContractMatchingBuilder
 
 ### constructor