Update documentation

Author: jc21

docs/advanced-config/README.md

@@ -1,5 +1,26 @@
 # Advanced Configuration
 
+## Running processes as a user/group
+
+By default, the services (nginx etc) will run as `root` user inside the docker container.
+You can change this behaviour by setting the following environment variables.
+Not only will they run the services as this user/group, they will change the ownership
+on the `data` and `letsencrypt` folders at startup.
+
+```yml
+services:
+  app:
+    image: 'jc21/nginx-proxy-manager:latest'
+    environment:
+      PUID: 1000
+      PGID: 1000
+    # ...
+```
+
+This may have the side effect of a failed container start due to permission denied trying
+to open port 80 on some systems. The only course to fix that is to remove the variables
+and run as the default root user.
+
 ## Best Practice: Use a Docker network
 
 For those who have a few of their upstream services running in Docker on the same Docker

docs/setup/README.md

@@ -64,9 +64,6 @@ services:
       # Add any other Stream port you want to expose
       # - '21:21' # FTP
     environment:
-      # Unix user and group IDs, optional
-      PUID: 1000
-      PGID: 1000
       # Mysql/Maria connection parameters:
       DB_MYSQL_HOST: "db"
       DB_MYSQL_PORT: 3306
@@ -90,7 +87,7 @@ services:
       MYSQL_USER: 'npm'
       MYSQL_PASSWORD: 'npm'
     volumes:
-      - ./data/mysql:/var/lib/mysql
+      - ./mysql:/var/lib/mysql
 ```
 
 ::: warning