doc: fix a typo in api/process.md

Fix a mistyped module name in example REPL sessions found in the
description of the 'warning' event: it should be `events` instead of
`event`.

PR-URL: nodejs#11780
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: sabakugaara

doc/api/process.md

@@ -298,7 +298,7 @@ too many listeners have been added to an event
 
 ```txt
 $ node
-> event.defaultMaxListeners = 1;
+> events.defaultMaxListeners = 1;
 > process.on('foo', () => {});
 > process.on('foo', () => {});
 > (node:38638) Warning: Possible EventEmitter memory leak detected. 2 foo
@@ -311,7 +311,7 @@ adds a custom handler to the `'warning'` event:
 ```txt
 $ node --no-warnings
 > var p = process.on('warning', (warning) => console.warn('Do not do that!'));
-> event.defaultMaxListeners = 1;
+> events.defaultMaxListeners = 1;
 > process.on('foo', () => {});
 > process.on('foo', () => {});
 > Do not do that!