Open Match Docs landing page is a bit sparse

[roberthbailey]

As mentioned in the issue title, https://development.open-match.dev/site/docs/ is a bit sparse and doesn't really tell me much about where I should be going next.

Ideas (mainly based on comparing with the similar docs landing page for Agones):

• Add some text to describe the page in a bit more detail
• Put the release version at the top of the page instead of the bottom.
• Instead of a bulleted list of links to other pages, make them section titles with brief descriptions about who should click the link and why