Add args to docker-compose as suggested in #285

Change-Id: I67083d86ea45c15b02f8db54a1649dbb013c3d50

docker-compose.yml

@@ -12,10 +12,14 @@ services:
     # replace the context definition with this:
     # context: https://github.com/Awesome-Technologies/synapse-admin.git
 
+    # args:
       # if you're building on an architecture other than amd64, make sure
       # to define a maximum ram for node. otherwise the build will fail.
-    # args:
       # - NODE_OPTIONS="--max_old_space_size=1024"
+      # default is /
+      # - PUBLIC_URL=/synapse-admin
+      # You can use a fixed homeserver, so that the user can no longer define it himself
+      # - REACT_APP_SERVER="https://matrix.example.com"
     ports:
       - "8080:80"
     restart: unless-stopped