Added full docs for new ENVIRONMENT constant.
diff --git a/user_guide/installation/index.html b/user_guide/installation/index.html
index 9a611eb..8ba4131 100644
--- a/user_guide/installation/index.html
+++ b/user_guide/installation/index.html
@@ -74,6 +74,12 @@
<p>After moving them, open your main <kdb>index.php</kbd> file and set the <samp>$system_folder</samp> and <samp>$application_folder</samp> variables, preferably with a full path, e.g. '<dfn>/www/MyUser/system</dfn>'.</p>
+<p>
+ One additional measure to take in production environments is to disable
+ PHP error reporting and any other development-only functionality. In CodeIgniter,
+ this can be done by setting the <kbd>ENVIRONMENT</kbd> constant, which is
+ more fully described on the <a href="../general/security.html">security page</a>.
+</p>
<p>That's it!</p>