Add a subscribe link for releases to teku landing page, potentially also (X)twitter ref.

[rolfyone]

ref. https://consensys.io/teku

just looking at removing a stale page, and one thing that it does seem to have is a subscribe that points to https://pages.consensys.net/teku-sign-up which allows signing up for release notifications.

It also has a link to follow on twitter https://twitter.com/teku_consensys and a different discord invite link (https://discord.gg/consensys) - Im not sure which is a better link for discord, just capturing here...

I think if we can add the release notification subscription and twitter reference, that the teku landing page on consensys.io is no longer required, and I can get that page removed (or redirect to docs) in preference to the docs landing page - I'm assuming these couple of things are fairly minor to accomplish?

[bgravenorst]

For the docs team:

• On the Teku landing page (and/or elsewhere, if more suitable), add a link to email list so that users can subscribe to Teku releases (https://share.hsforms.com/1bkXI6uLpSROGBRVig4KeIQ2urwb)
• Confirm that the Discord link is correct
• Add a Twitter(X) icon link to the top right of the landing page.