Use Alpine Linux in examples and use default user

Signed-off-by: J0WI <J0WI@users.noreply.github.com>
Signed-off-by: marceljd <support@dihosting.ch>

.examples/docker-compose/insecure/postgres/fpm/web/Dockerfile

@@ -1,3 +1,3 @@
-FROM nginx
+FROM nginx:alpine
 
 COPY nginx.conf /etc/nginx/nginx.conf

.examples/docker-compose/insecure/postgres/fpm/web/nginx.conf

@@ -1,4 +1,3 @@
-user  www-data;
 worker_processes  1;
 
 error_log  /var/log/nginx/error.log warn;