docs: add changelog

Author: kenjis

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## [v4.1.9](https://github.com/codeigniter4/CodeIgniter4/tree/v4.1.9) (2022-02-xx)
+
+[Full Changelog](https://github.com/codeigniter4/CodeIgniter4/compare/v4.1.8...v4.1.9)
+
+**SECURITY**
+
+* *Remote CLI Command Execution Vulnerability* was fixed. See the [Security advisory](https://github.com/codeigniter4/CodeIgniter4/security/advisories/GHSA-xjp4-6w75-qrj7) for more information.
+
 ## [v4.1.8](https://github.com/codeigniter4/CodeIgniter4/tree/v4.1.8) (2022-01-24)
 
 [Full Changelog](https://github.com/codeigniter4/CodeIgniter4/compare/v4.1.7...v4.1.8)

user_guide_src/source/changelogs/index.rst

@@ -12,6 +12,7 @@ See all the changes.
 .. toctree::
     :titlesonly:
 
+    v4.1.9
     v4.1.8
     v4.1.7
     v4.1.6

user_guide_src/source/changelogs/v4.1.9.rst

@@ -0,0 +1,15 @@
+Version 4.1.9
+#############
+
+Release Date: February xx, 2022
+
+**4.1.9 release of CodeIgniter4**
+
+.. contents::
+    :local:
+    :depth: 2
+
+SECURITY
+********
+
+- *Remote CLI Command Execution Vulnerability* was fixed. See the `Security advisory <https://github.com/codeigniter4/CodeIgniter4/security/advisories/GHSA-xjp4-6w75-qrj7>`_ for more information.

user_guide_src/source/installation/upgrading.rst

@@ -8,6 +8,7 @@ upgrading from.
 .. toctree::
     :titlesonly:
 
+    Upgrading from 4.1.7 to 4.1.8 <upgrade_418>
     Upgrading from 4.1.6 to 4.1.7 <upgrade_417>
     Upgrading from 4.1.5 to 4.1.6 <upgrade_416>
     Upgrading from 4.1.4 to 4.1.5 <upgrade_415>