Move 1.0 documentation under 0.16

[orkunkl]

Currently we have two version of documentation.

• 1.0: new smart contract and version documentation https://github.com/InterWasm/docs/tree/main/docs and https://docs.cosmwasm.com/docs/1.0/getting-started/intro
• 0.16: tracks cosmwasm-std 0.16 https://github.com/InterWasm/docs/tree/main/docs_versioned_docs/version-0.16 and https://docs.cosmwasm.com/docs/0.16/getting-started/intro

0.16 version is not easily found so lower click rate.

• Move 1.0 changes to 0.16 @kaymakf
• Redirect 1.0 to 0.16 @orkunkl

[orkunkl]

Let's collaborate on a branch, then merge it in one piece @kaymak.