docs: Replace ProgramAccount with Account in tutorial-2.md (#760)

docs/src/tutorials/tutorial-2.md

@@ -13,7 +13,7 @@ To address these problems, Anchor provides several types, traits, and macros. It
 from the untrusted `&[AccountInfo]` slice given to a Solana program into a validated struct
 of deserialized account types.
 * [#[account]](https://docs.rs/anchor-lang/latest/anchor_lang/attr.account.html): attribute macro implementing [AccountSerialize](https://docs.rs/anchor-lang/latest/anchor_lang/trait.AccountSerialize.html) and [AccountDeserialize](https://docs.rs/anchor-lang/latest/anchor_lang/trait.AnchorDeserialize.html), automatically prepending a unique 8 byte discriminator to the account array. The discriminator is defined by the first 8 bytes of the `Sha256` hash of the account's Rust identifier--i.e., the struct type name--and ensures no account can be substituted for another.
-* [ProgramAccount](https://docs.rs/anchor-lang/latest/anchor_lang/struct.ProgramAccount.html): a wrapper type for a deserialized account implementing `AccountDeserialize`. Using this type within an `Accounts` struct will ensure the account is **owned** by the currently executing program.
+* [Account](https://docs.rs/anchor-lang/latest/anchor_lang/struct.Account.html): a wrapper type for a deserialized account implementing `AccountDeserialize`. Using this type within an `Accounts` struct will ensure the account is **owned** by the currently executing program.
 
 With the above, we can define preconditions for our any instruction handler expecting a certain set of
 accounts, allowing us to more easily reason about the security of our programs.
@@ -47,7 +47,7 @@ Let's focus on the `increment` instruction, specifically the `Increment` struct
 #[derive(Accounts)]
 pub struct Increment<'info> {
     #[account(mut, has_one = authority)]
-    pub counter: ProgramAccount<'info, Counter>,
+    pub counter: Account<'info, Counter>,
     #[account(signer)]
     pub authority: AccountInfo<'info>,
 }