Update landing page and TOCList

[BorghildSelle]

• Add optional group ingress to Edit Menu group
• Add optional ingress (block with links) to Menu link
• Add choose variant to menu group:
  • 'card' : update card to use the core card component
  • 'textblock': new comp to look like https://www.sanity.io/docs/sanity-studio, https://www.sanity.io/docs/user-guide . Which we can use in the editorial documentation, intranet information/faq pages. Except keep the arrow to the bottom right like the 'card'.

Textblock variant spec:

• add option to hide/show links in the "textblock card"

Check if we could make a simple left side TOC list by using the menugroup label + connecting it with anchor link for it, and the sub links label + connecting it with its link to page