docs: document the repl "exit" event

doc/api/repl.markdown

@@ -29,8 +29,8 @@ For example, you could add this to your bashrc file:
 
 ## repl.start([prompt], [stream], [eval], [useGlobal], [ignoreUndefined])
 
-Starts a REPL with `prompt` as the prompt and `stream` for all I/O.  `prompt`
-is optional and defaults to `> `.  `stream` is optional and defaults to
+Returns and starts a REPL with `prompt` as the prompt and `stream` for all I/O.
+`prompt` is optional and defaults to `> `.  `stream` is optional and defaults to
 `process.stdin`. `eval` is optional too and defaults to async wrapper for
 `eval()`.
 
@@ -76,6 +76,20 @@ TCP sockets.
 By starting a REPL from a Unix socket-based server instead of stdin, you can
 connect to a long-running node process without restarting it.
 
+### Event: 'exit'
+
+`function () {}`
+
+Emitted when the user exits the REPL in any of the defined ways. Namely, typing
+`.exit` at the repl, or pressing Ctrl+C twice to signal SIGINT.
+
+Example of listening for `exit`:
+
+    r.on('exit', function () {
+      console.log('Got "exit" event from repl!');
+      process.exit();
+    });
+
 
 ## REPL Features