chore: Update docker-php-serversideup-set-file-permissions script name in documentation

Author: jaydrogers

docs/content/docs/3.guide/2.understanding-file-permissions.md

@@ -29,7 +29,7 @@ It's a bummer that we can only set the user and group ID at build time, but it's
 #### How it works
 - By default, all our images run `www-data` as the user (`33:33` for Debian and `82:82` for Alpine)
 - We provide a script that can be called at build time to change the UID and GID of `www-data` (called `docker-php-serversideup-set-id`)
-- If you need to update permissions of service files (example: NGINX, Apache, Unit, etc), you can run the `docker-php-serversideup-set-id` at build
+- If you need to update permissions of service files (example: NGINX, Apache, Unit, etc), you can run the `docker-php-serversideup-set-file-permissions` at build
 - We will use a multi-stage build to ensure that the `docker-php-serversideup-set-id` script is not included in the final image
 
 ## Example