Add hostname to docker-compose

If this is not set, the PiHole admin page shows the Docker container's 
ID as hostname instead.

README.md

@@ -18,6 +18,7 @@ services:
   pihole:
     container_name: pihole
     image: pihole/pihole:latest
+    hostname: pihole
     ports:
       - "53:53/tcp"
       - "53:53/udp"

docker-compose-jwilder-proxy.yml

@@ -5,6 +5,7 @@ version: "3"
 services:
   jwilder-proxy:
     image: jwilder/nginx-proxy
+    hostname: pihole.yourDomain.lan
     ports:
       - '80:80'
     environment:

docker-compose.yml.example

@@ -6,6 +6,7 @@ services:
   pihole:
     container_name: pihole
     image: pihole/pihole:latest
+    hostname: pihole
     # For DHCP it is recommended to remove these ports and instead add: network_mode: "host"
     ports:
       - "53:53/tcp"