docs: Revamp ROFL chapter slightly to also include smart contract deployment

[matevz]

A user asked an interesting chickend-and-agg problem which I also considered a while ago:

(According to docs) Basically I need to first open the docker local testnet via sudo docker run -it -p8545:8545 -p8546:8546 -v ./rofl-oracle:/rofls ghcr.io/oasisprotocol/sapphire-localnet
Then deploy a sapphire contract like the one you gave by changin the http provider.
So lets say now I do get an address x of this contract but now I will change the address to this one inside the rofl application like in the docs and build it.
After this I need to again run the local test net but this time by running the docker instance with the rolf app mounted.
My question is does turing my local testnet off then turning it on again not refreshes it completely? Or does my deployed contract on local testnet remain even after stoping the docker instance and loading it again with the rolf app mounted for price updation purposes?

My answer on this was:

the contract address is derived from the address of the account it's deploying it and nonce. This will always be deterministic on Localnet when you restart it.

I suggest we:

• Put a note somewhere that the contract address will always be deterministic on the Localnet, if you're using the same account and that's why you can simply hardcode the smart contract address into the ROFL rust source.
• Put the hardhat deploy somewhere into the Application chapter already so that people can try the complete example without reading through the whole Deployment chapter