Deprecate Docs until new maintainers exist

[ethanfrey]

This repo is served under docs.cosmwasm.com and has barely been updated the last year.
We have gotten lots of complaints about confusion and issues from it.

The CosmWasm core team proposes to replace the menu and landing page with a large deprecated notice, directing people to more up-to-date sources of information, such as book.cosmwasm.com (on contract development), cw-awesome (on 3rd party resources), CosmWasm academy and solid Youtube videos.

It would be useful to have a step-by-step guide to show people how to set up a local blockchain and deploy contracts, but what is in these docs is no longer best practice. All smart contract development work should go to book.cosmwasm.com and this should serve to direct people there and provide other setup info:

• Run local dev net
• Connect to various testnets
• Connect to various main nets
• Learning resources
• Links to other teaching sources (eg book)

However, until there is an active maintainer that has prepared such info in a PR, we can leave a deprecated notice.

I know @JakeHartnell was looking to find a new maintainer and I welcome that. But I still want to place the deprecation notice on the main page until that maintainer is found and is active. This site is way overdue for an overhaul.

[ethanfrey]

Looks like you did this.

[0xFable]

I am going to take a crack at some of the above and getting the docs ready for un-deprecation!!