[ci skip] Change some log messages' level

'Class Loaded' type of messages flood log files when
log_threshold is set to 2 (debug). They're now logged
as 'info' level.

This is manually applying PR #1528, which was created
to do the same thing, but became outdated.
diff --git a/user_guide_src/source/general/errors.rst b/user_guide_src/source/general/errors.rst
index 26c26be..721c78c 100644
--- a/user_guide_src/source/general/errors.rst
+++ b/user_guide_src/source/general/errors.rst
@@ -101,9 +101,7 @@
    example, if a class has been initialized, you could log this as
    debugging info.
 #. Informational Messages. These are the lowest priority messages,
-   simply giving information regarding some process. CodeIgniter doesn't
-   natively generate any info messages but you may want to in your
-   application.
+   simply giving information regarding some process.
 
 .. note:: In order for the log file to actually be written, the *logs*
 	directory must be writable. In addition, you must set the "threshold"