Merge pull request #5727 from kenjis/fix-docs-previous-version

docs: change "previous version" to a specific version

Author: kenjis

user_guide_src/source/libraries/sessions.rst

@@ -69,7 +69,7 @@ Unless you're developing a website with heavy AJAX usage, you can skip this
 section. If you are, however, and if you're experiencing performance
 issues, then this note is exactly what you're looking for.
 
-Sessions in previous versions of CodeIgniter didn't implement locking,
+Sessions in CodeIgniter v2.x didn't implement locking,
 which meant that two HTTP requests using the same session could run exactly
 at the same time. To use a more appropriate technical term - requests were
 non-blocking.

user_guide_src/source/libraries/uploaded_files.rst

@@ -5,7 +5,7 @@ Working with Uploaded Files
 CodeIgniter makes working with files uploaded through a form much simpler and more secure than using PHP's ``$_FILES``
 array directly. This extends the :doc:`File class </libraries/files>` and thus gains all of the features of that class.
 
-.. note:: This is not the same as the File Uploading class in previous versions of CodeIgniter. This provides a raw
+.. note:: This is not the same as the File Uploading class in CodeIgniter v3.x. This provides a raw
     interface to the uploaded files with a few small features.
 
 .. contents::