docs: update user guide

Author: kenjis

user_guide_src/source/installation/installing_composer.rst

@@ -7,6 +7,8 @@ Composer Installation
 
 Composer can be used in several ways to install CodeIgniter4 on your system.
 
+.. important:: CodeIgniter4 requires Composer 2.0.14 or later.
+
 The first technique describes creating a skeleton project
 using CodeIgniter4, that you would then use as the base for a new webapp.
 The second technique described below lets you add CodeIgniter4 to an existing

user_guide_src/source/installation/upgrade_430.rst

@@ -12,16 +12,14 @@ Please refer to the upgrade instructions corresponding to your installation meth
     :local:
     :depth: 2
 
-Trouble Shooting
+Composer Version
 ****************
 
-Call to undefined method Composer\\InstalledVersions::getAllRawData()
-=====================================================================
+.. important:: If you use Composer Installation, CodeIgniter v4.3.0 requires
+    Composer 2.0.14 or later.
 
-Some users reported "*Fatal error: Uncaught Error: Call to undefined method Composer\\InstalledVersions::getAllRawData()*" after upgrading with Composer.
-
-If you get the error, upgrade your ``composer`` tool, and delete the **vendor/**
-directory, and run ``composer update`` again.
+If you are using older version of Composer, upgrade your ``composer`` tool,
+and delete the **vendor/** directory, and run ``composer update`` again.
 
 The procedure, for example, is as follows::