add missing backslash in the quickstart guide and update autoconf examples with the depends_on directive

examples/autoconf-php/docker-compose.yml

@@ -31,6 +31,9 @@ services:
       - autoconf:/etc/nginx
     depends_on:
       - mywww
+      - myapp1
+      - myapp2
+      - myapp3
 
   myapp1:
     image: php:fpm

examples/autoconf-reverse-proxy/docker-compose.yml

@@ -32,6 +32,9 @@ services:
       - autoconf:/etc/nginx
     depends_on:
       - mywww
+      - myapp1
+      - myapp2
+      - myapp3
 
   myapp1:
     build: js-app