message: update process exits on readme.md
diff: @@ -152,6 +152,12 @@ await matic.withdraw(
  txId, // Transaction id generated from the 'startWithdraw' method
  options // transaction fields
  )
  +
  +// Process exits after completion of challenge period
  +await matic.processExits(
  + rootTokenAddress, // RootToken address
  + options // transaction fields
  +)
  ```
  ### How it works?
  @@ -198,6 +204,7 @@ Please write to info@matic.network to request TEST tokens for development purpos
  - <a href="#startERC721Withdraw"><code>matic.<b>startERC721Withdraw()</b></code></a>
  - <a href="#getHeaderObject"><code>matic.<b>getHeaderObject()</b></code></a>
  - <a href="#withdraw"><code>matic.<b>withdraw()</b></code></a>
  +- <a href="#processExits"><code>matic.<b>processExits()</b></code></a>
  - <a href="#getTx"><code>matic.<b>getTx()</b></code></a>
  - <a href="#getReceipt"><code>matic.<b>getReceipt()</b></code></a>
  @@ -227,7 +234,7 @@ const matic = new Matic(options)
  - `rootChainAddress` must be valid Ethereum contract address.
  - `syncerUrl` must be valid API host. MaticSDK uses this value to fetch receipt/tx proofs instead of getting whole block to client side.
  - `watcherUrl` must be valid API host. MaticSDK uses this value to fetch headerBlock info from mainchain and to find appropriate headerBlock for given blockNumber.
  -
  + - `withdrawManagerAddress` must be valid Ethereum contract address.
  ---
  <a name="getMappedTokenAddress"></a>
  @@ -629,6 +636,27 @@ matic.withdraw("0xabcd...789", {
  ---
  +<a name="processExits"></a>
  +
  +#### matic.processExits(rootTokenAddress, options)
  +
  +Call process Exits after completion of challenge period, after that withdrawn funds get transfered on mainchain
  +
  +- `rootTokenAddress` RootToken address
  +- `options` see [more infomation here](#approveERC20TokensForDeposit)
  +
  +This returns `Promise` object, which will be fulfilled when transaction gets confirmed (when receipt is generated).
  +
  +Example:
  +
  +```js
  +matic.processExits("0xabcd...789", {
  + from: "0xABc578455..."
  +})
  +```
  +
  +---
  +
  <a name="getTx"></a>
  #### matic.getTx(txId)
  