Document decks more specifically

[bernhold]

We should make sure the decks are documented properly. Some of the key points...

• Decks should be short (~1 sentence)e as a teaser, to give the user a reason to read further
• The first paragraph of the article is treated as the deck.
  • Except in blog articles with a hero image, in which case there is no deck
• A useful convention in the source is to place the deck before the Contributed by and Publication date headings.
• Another common convention in the source is to bracket the deck with HTML comments
• But it is important to be aware that neither the position nor the comments have any impact on how the frontend interprets the source -- the first paragraph is formatted as the deck, except for blog articles with hero images.