chore(readme): add file events to docs

README.md

@@ -125,7 +125,7 @@ The `FtpSrv` class extends the [node net.Server](https://nodejs.org/api/net.html
 
 ### `login`
 ```js
-on('login', {connection, username, password}, resolve, reject) => { ... }
+on('login', ({connection, username, password}, resolve, reject) => { ... });
 ```
 
 Occurs when a client is attempting to login. Here you can resolve the login request by username and password.
@@ -152,7 +152,7 @@ Occurs when a client is attempting to login. Here you can resolve the login requ
 
 ### `client-error`
 ```js
-on('client-error', {connection, context, error}) => { ... }
+on('client-error', ({connection, context, error}) => { ... });
 ```
 
 Occurs when an error arises in the client connection.
@@ -161,6 +161,26 @@ Occurs when an error arises in the client connection.
 `context` string of where the error occured  
 `error` error object
 
+### `RETR`
+```js
+on('RETR', (error, filePath) => { ... });
+```
+
+Occurs when a file is downloaded.
+
+`error` if successful, will be `null`
+`filePath` location to which file was downloaded
+
+### `STOR`
+```js
+on('STOR', (error, fileName) => { ... });
+```
+
+Occurs when a file is uploaded.
+
+`error` if successful, will be `null`
+`fileName` name of the file that was downloaded
+
 ## Supported Commands
 
 See the [command registry](src/commands/registration) for a list of all implemented FTP commands.