Explain smart contract sample

[NicolasMassart]

• add a little explanation regarding the counter.sol smart contract thats going to be compiled
• can we change the wording of ‘Push artifacts’ to something more understandable?
• on ‘deploy smart contract’ make it bigger, bolder, clear that what the terminal image is giving us back is the ‘smart contract receipt’ and point to its address
• on step to update .env TO_ACCOUNT at contract address, indicate its talking about the address shown on the receipt coming back from the terminal