Remove parity specific bit in nginx file (not needed anyway), name default network, tweak a dockerfile comment

docker-compose.yml

@@ -1,5 +1,10 @@
 version: "3"
 
+networks:
+  default:
+    # Give the default network created below a sensible name:
+    name: substrate-telemetry
+
 services:
   telemetry-frontend:
     build:

frontend/Dockerfile

@@ -15,8 +15,8 @@ FROM docker.io/nginx:stable-alpine
 LABEL maintainer="Chevdor <chevdor@gmail.com>"
 LABEL description="Polkadot Telemetry frontend"
 
-# When we run the built docker image, the default command uses this
-# env var to tell the UI where to look to get feed info.
+# Each time this container is ran, the value that's provided for this env var
+# determines where the frontend will try to request feed information from:
 ENV SUBSTRATE_TELEMETRY_URL=
 
 WORKDIR /usr/share/nginx/html

frontend/nginx/nginx.conf

@@ -29,6 +29,5 @@ http {
         index index.html;
         listen 8000;
         listen [::]:8000;
-        server_name telemetry.polkadot.io localhost;
     }
 }