Added note about configuring nginx for HTTPS

docs/guide/installation.md

@@ -122,7 +122,7 @@ an [FPM SAPI](http://php.net/install.fpm). Below is a sample host configuration
 The configuration tells the server to send all requests for non-existent resources through the bootstrap file,
 resulting in "prettier" URLs without the need for `index.php` references.
 
-~~~
+```
 server {
     set $yii_bootstrap "index.php";
     charset utf-8;
@@ -159,6 +159,10 @@ server {
         deny all;
     }
 }
-~~~
+```
 
 When using this configuration, you should set `cgi.fix_pathinfo=0` in the `php.ini` file in order to avoid many unnecessary system `stat()` calls.
+
+
+Note that when running HTTP server you need to add `fastcgi_param HTTPS on;` in order for Yii to properly detect if
+connection is secure.