[ci skip] Make it clear that PHP <5.4 usage is discouraged

Related: #3450

5 files changed, 25 insertions, 16 deletions

diff --git a/contributing.md b/contributing.md
index 5296daa88..5a25698bf 100644
--- a/contributing.md
+++ b/contributing.md
@@ -29,10 +29,10 @@ If you change anything that requires a change to documentation then you will nee
 
 ### Compatibility
 
-CodeIgniter recommends PHP 5.4 or newer to be used, but is is compatible with
-PHP 5.2.4 so all code supplied must stick to this requirement. If PHP 5.3
-(and above) functions or features are used then there must be a fallback for
-PHP 5.2.4.
+CodeIgniter recommends PHP 5.4 or newer to be used, but it should be
+compatible with PHP 5.2.4 so all code supplied must stick to this
+requirement. If PHP 5.3 (and above) functions or features are used then
+there must be a fallback for PHP 5.2.4.
 
 ### Branching
 
diff --git a/readme.rst b/readme.rst
index c32961448..dd59fd8c1 100644
--- a/readme.rst
+++ b/readme.rst
@@ -29,7 +29,11 @@ guide change log <https://github.com/bcit-ci/CodeIgniter/blob/develop/user_guide
 Server Requirements
 *******************
 
--  PHP version 5.2.4 or newer.
+PHP version 5.4 or newer is recommended.
+
+It should work on 5.2.4 as well, but we strongly advise you NOT to run
+such old versions of PHP, because of potential security and performance
+issues, as well as missing features.
 
 ************
 Installation
diff --git a/user_guide_src/source/contributing/index.rst b/user_guide_src/source/contributing/index.rst
index 89bceaa61..e88147753 100644
--- a/user_guide_src/source/contributing/index.rst
+++ b/user_guide_src/source/contributing/index.rst
@@ -92,10 +92,10 @@ must also be updated for every change. Also PHPDoc blocks must be maintained.
 Compatibility
 =============
 
-CodeIgniter recommends PHP 5.4 or newer to be used, but is compatible with
-PHP 5.2.4 so all code supplied must stick to this requirement. If PHP 5.3
-(and above) functions or features are used then there must be a fallback
-for PHP 5.2.4.
+CodeIgniter recommends PHP 5.4 or newer to be used, but it should be
+compatible with PHP 5.2.4 so all code supplied must stick to this
+requirement. If PHP 5.3 (and above) functions or features are used then
+there must be a fallback for PHP 5.2.4.
 
 Branching
 =========
diff --git a/user_guide_src/source/general/requirements.rst b/user_guide_src/source/general/requirements.rst
index 1cb5938aa..e3f73dba8 100644
--- a/user_guide_src/source/general/requirements.rst
+++ b/user_guide_src/source/general/requirements.rst
@@ -2,10 +2,15 @@
 Server Requirements
 ###################
 
-- `PHP <http://www.php.net/>`_ version 5.4 or newer is recommended and 5.2.4 as the absolute minimum required.
-- A Database is required for most web application programming.
+`PHP <http://www.php.net/>`_ version 5.4 or newer is recommended.
+
+It should work on 5.2.4 as well, but we strongly advise you NOT to run
+such old versions of PHP, because of potential security and performance
+issues, as well as missing features.
+
+A database is required for most web application programming.
+Currently supported databases are:
 
- Currently supported databases are:
   - MySQL (5.1+) via the *mysql* (deprecated), *mysqli* and *pdo* drivers
   - Oracle via the *oci8* and *pdo* drivers
   - PostgreSQL via the *postgre* and *pdo* drivers
diff --git a/user_guide_src/source/general/styleguide.rst b/user_guide_src/source/general/styleguide.rst
index 3d8f0a78a..b27031a7b 100644
--- a/user_guide_src/source/general/styleguide.rst
+++ b/user_guide_src/source/general/styleguide.rst
@@ -368,10 +368,10 @@ inability for CodeIgniter to send proper headers.
 Compatibility
 =============
 
-CodeIgniter recommends PHP 5.4 or newer to be used, but the absolute
-minimum version required is 5.2.4. Your code must either be compatible
-with this minimum requirement, provide a suitable fallback, or be an
-optional feature that dies quietly without affecting a user's application.
+CodeIgniter recommends PHP 5.4 or newer to be used, but it should be
+compatible with PHP 5.2.4. Your code must either be compatible with this
+requirement, provide a suitable fallback, or be an optional feature that
+dies quietly without affecting a user's application.
 
 Additionally, do not use PHP functions that require non-default libraries
 to be installed unless your code contains an alternative method when the