docs: replace Nginx with nginx

It seems all lower case is the official.

Author: kenjis

user_guide_src/source/general/environments.rst

@@ -75,10 +75,10 @@ config using `SetEnv <https://httpd.apache.org/docs/2.4/mod/mod_env.html#setenv>
 
 .. _environment-nginx:
 
-Nginx
+nginx
 -----
 
-Under Nginx, you must pass the environment variable through the ``fastcgi_params``
+Under nginx, you must pass the environment variable through the ``fastcgi_params``
 in order for it to show up under the ``$_SERVER`` variable. This allows it to work on the
 virtual-host level, instead of using `env` to set it for the entire server, though that
 would work fine on a dedicated server. You would then modify your server config to something
@@ -97,7 +97,7 @@ like:
         }
     }
 
-Alternative methods are available for Nginx and other servers, or you can
+Alternative methods are available for nginx and other servers, or you can
 remove this logic entirely and set the constant based on the server's IP address
 (for instance).
 

user_guide_src/source/general/urls.rst

@@ -95,10 +95,10 @@ request for your index.php file.
 
 .. _urls-remove-index-php-nginx:
 
-NGINX
+nginx
 -----
 
-Under NGINX, you can define a location block and use the ``try_files`` directive to get the same effect as we did with
+Under nginx, you can define a location block and use the ``try_files`` directive to get the same effect as we did with
 the above Apache configuration:
 
 .. code-block:: nginx

user_guide_src/source/installation/running.rst

@@ -59,7 +59,7 @@ in **.env** file to take advantage of the debugging tools provided. See
 Setting Writable Folder Permission
 ==================================
 
-If you will be running your site using a web server (e.g., Apache or Nginx),
+If you will be running your site using a web server (e.g., Apache or nginx),
 you will need to modify the permissions for the **writable** folder inside
 your project, so that it is writable by the user or account used by your
 web server.
@@ -368,10 +368,10 @@ Setting Environment
 See :ref:`Handling Multiple Environments <environment-apache>`.
 
 ******************
-Hosting with Nginx
+Hosting with nginx
 ******************
 
-Nginx is the second most widely used HTTP server for web hosting.
+nginx is the second most widely used HTTP server for web hosting.
 Here you can find an example configuration using PHP 8.1 FPM (unix sockets) under Ubuntu Server.
 
 default.conf

user_guide_src/source/tutorial/index.rst

@@ -92,7 +92,7 @@ Running Development Server
 ==========================
 
 With that out of the way it's time to view your application in a browser. You can
-serve it through any server of your choice, Apache, Nginx, etc, but CodeIgniter
+serve it through any server of your choice, Apache, nginx, etc, but CodeIgniter
 comes with a simple command that takes advantage of PHP's built-in server to get
 you up and running fast on your development machines. Type the following on the
 command line from the root of your project: