[ci skip] Clarify comments about libraries/drivers autoloading
Close #3964
diff --git a/application/config/autoload.php b/application/config/autoload.php
index 3f0bd24..4bc6bf0 100644
--- a/application/config/autoload.php
+++ b/application/config/autoload.php
@@ -45,8 +45,9 @@
| -------------------------------------------------------------------
| Auto-load Libraries
| -------------------------------------------------------------------
-| These are the classes located in the system/libraries folder
-| or in your application/libraries folder.
+| These are the classes located in system/libraries/ or your
+| application/libraries/ directory, with the addition of the
+| 'database' library, which is somewhat of a special case.
|
| Prototype:
|
@@ -63,8 +64,9 @@
| -------------------------------------------------------------------
| Auto-load Drivers
| -------------------------------------------------------------------
-| These classes are located in the system/libraries folder or in your
-| application/libraries folder within their own subdirectory. They
+| These classes are located in system/libraries/ or in your
+| application/libraries/ directory, but are also placed inside their
+| own subdirectory and they extend the CI_Driver_Library class. They
| offer multiple interchangeable driver options.
|
| Prototype: