doc: update fs.open() changes record for optional 'flags'

rvagg · rvagg · commit 4c9089d2a201 · 2018-11-12T12:20:31.000+11:00
Was missed on original PR. Ref: nodejs#23767
diff --git a/doc/api/fs.md b/doc/api/fs.md
@@ -2313,6 +2313,9 @@ object with an `encoding` property specifying the character encoding to use.
 <!-- YAML
 added: v0.0.2
 changes:
+  - version: v11.1.0
+    pr-url: https://github.com/nodejs/node/pull/23767
+    description: The `flags` argument is now optional and defaults to `'r'`
   - version: v9.9.0
     pr-url: https://github.com/nodejs/node/pull/18801
     description: The `as` and `as+` modes are supported now.
