Smart Contracts documentation

[juangirini]

In the context of the Developer Hub, Smart Contracts documentation is needed.
It should include:

• WASM and EVM based, pallet-contracts and pallet-evm.
• single-daap-chain, transition from ink! to FRAME.
• Link to use.ink
• Link to [crate::reference_docs::runtime_vs_smart_contract].
• https://use.ink/migrate-ink-contracts-to-polkadot-frame-parachain/

https://github.com/paritytech/polkadot-sdk/blob/94eeed60830808c3e1d1c8043c49cd6af20b18ce/developer-hub/src/polkadot_sdk/smart_contracts.rs