docs: privacy APIs

Author: chetan

docs/api.md

@@ -1,6 +1,57 @@
 
 # API
 
+## Privacy APIs
+
+### `web3.eth.sendTransaction(object)` was modified to support private transactions
+
+```js
+web3.eth.sendTransaction(transactionObject [, callback])
+```
+
+Sends a transaction to the network.
+
+##### Parameters
+
+1. `Object` - The transaction object to send:
+  - `from`: `String` - The address for the sending account. Uses the [web3.eth.defaultAccount](#web3ethdefaultaccount) property, if not specified.
+  - `to`: `String` - (optional) The destination address of the message, left undefined for a contract-creation transaction.
+  - `value`: `Number|String|BigNumber` - (optional) The value transferred for the transaction in Wei, also the endowment if it's a contract-creation transaction.
+  - `gas`: `Number|String|BigNumber` - (optional, default: To-Be-Determined) The amount of gas to use for the transaction (unused gas is refunded).
+  - <strike>`gasPrice`: `Number|String|BigNumber` - (optional, default: To-Be-Determined) The price of gas for this transaction in wei, defaults to the mean network gas price.</strike>
+  - `data`: `String` - (optional) Either a [byte string](https://github.com/ethereum/wiki/wiki/Solidity,-Docs-and-ABI) containing the associated data of the message, or in the case of a contract-creation transaction, the initialisation code.
+  - `nonce`: `Number`  - (optional) Integer of a nonce. This allows to overwrite your own pending transactions that use the same nonce.
+  - `privateFrom`: `String`  - (optional) When sending a private transaction, the sending party's base64-encoded public key to use. If not present *and* passing `privateFor`, use the default key as configured in the `TransactionManager`.
+  - `privateFor`: `List<String>`  - (optional) When sending a private transaction, an array of the recipients' base64-encoded public keys.
+2. `Function` - (optional) If you pass a callback the HTTP request is made asynchronous. See [this note](#using-callbacks) for details.
+
+##### Returns
+
+`String` - The 32 Bytes transaction hash as HEX string.
+
+If the transaction was a contract creation use [web3.eth.getTransactionReceipt()](#web3gettransactionreceipt) to get the contract address, after the transaction was mined.
+
+##### Example
+
+```js
+// compiled solidity source code using https://chriseth.github.io/cpp-ethereum/
+var code = "603d80600c6000396000f3007c01000000000000000000000000000000000000000000000000000000006000350463c6888fa18114602d57005b6007600435028060005260206000f3";
+
+web3.eth.sendTransaction({
+    data: code,
+    privateFor: ["ROAZBWtSacxXQrOe3FGAqJDyJjFePR5ce4TSIzmJ0Bc="]
+  },
+  function(err, address) {
+    if (!err) {
+      console.log(address); // "0x7f9fade1c0d57a7af66ab4ead7c2eb7b11a91385"
+    }
+  }
+});
+```
+
+
+## QuorumChain APIs
+
 Quorum provides an API to inspect the current state of the voting contract.
 
 ### `quorum.nodeInfo` returns the quorum capabilities of this node