Chapter 10 has invalid YAML syntax

[Nnemr]

Exercise
10.4
Problem
The syntax for labels is incorrect. When you run docker-compose -f ./docker-compose.yml -f ./docker-compose-prod.yml config, the following error occurs:

parsing /mnt/d/projects/diamol/ch10/exercises/image-gallery/docker-compose-prod.yml: yaml: unmarshal errors:
  line 9: mapping key "x-labels" already defined at line 3

Docker version
Docker version 24.0.6, build ed223bc

Code version

commit 71384f8c09a8e0b3867a2c73ae09549774a21e85 (HEAD -> nnemr/update-ch10-exercise, origin/master, origin/HEAD, master)
Author: Elton Stoneman <[email protected]>
Date:   Fri Mar 5 15:43:14 2021 +0000

    Bump Apache versions

[ChoiWheatley]

Since "x-labels" defined at line 3 and line 9, you can avoid duplicated keys:

x-logging: &logging
  logging:
    options:
      max-size: '100m'
      max-file: '10'

x-labels: &labels
  app-name: image-gallery