Snap descriptions do not support headers on website but do in the desktop app

[JGCarroll]

Expected behaviour

When updating the description of a snap on snapcraft.io, the snaps description in its listing page is stated to support markdown.

Whilst some markdown is supported, headers (#) seem to be broken on new uploads.

Steps to reproduce the problem

Update a snap description and have a header like

# I am a header

Markdown is **fun**

Notice how this is supported historically, e.g., https://snapcraft.io/notesnook (who I totally didn't borrow some inspiration from).

Specs

https://snapcraft.io/joplin-desktop

• Operating system:_ Ubuntu 24.0

• Browser: Firefox

• [X] This issue is related to the snapcraft.io website itself (and not a specific snap).