Fix: Clone who parameter before inserting into balances map

[0xScratch]

Within the lesson 3 of section 1, there's an error while we create the set_balance function for Pallet Struct. That's how the current code looks like (with an error):

and here's the fix, by replacing who with who.clone() within the insert method:

Two grammatical fixes are included...Thanks!

[0xScratch]

Just noticed another error while retrieving the balance using balance function of the Pallet struct:

This is likely the fix, replacement of &who with who:

pub fn balance(&self, who: &String) -> u128 {
    *self.balances.get(who).unwrap_or(&0)
}

[0xScratch]

Hey @nomadbitcoin, can you take a look at these PRs? They might be useful for developers to interact with these lessons within the program alongside me.

[nomadbitcoin]

you're right, I just tested it now and although the solutioj for the problem is correct the exercise is wrong, your update seems correct, thank you!

[nomadbitcoin]

you're right, I just tested it now and your update seems correct, thank you!