[archisha-g]

Fixes canonical/open-documentation-academy#377

What changed

• The goals list stays a bulleted list, since it is a complete set of equal requirements with no order. I added a lead-in sentence ("The image must meet these goals") so the list is introduced.
• The numbered list of build stages is now prose. It was a single sentence split across two numbered items, and it covered only two of the three stages (the final stage followed in a separate "Finally" paragraph). As one sentence, the whole sequence reads together, and the detailed numbered steps follow later on the page.

Why

The Ubuntu style guide says to use numbered lists only when order matters for steps the reader follows and bullets or prose otherwise. Only the "Design the image" section is changed.

[asanvaq]

Hi! Thank you for your contribution! It looks very good, I just have a small suggestion on the first list.

[archisha-g]

Thanks @asanvaq, I’ve applied your suggestion, and that reads much better. Let me know if anything else needs changing!