Bug docs: command examples use short options instead of long #2319

Docs for the following commands use examples with short options (eg. -o), instead of long (--output):

• cdn get
• cdn origin add
• cdn origin remove
• cdn policy list
• cdn policy set
• cdn set
• customaction add
• customaction clear
• customaction get
• customaction list
• customaction remove
• customaction set

This makes these docs less readable and user-friendly. We should update all examples to use long option names instead.