spelling issues (#182)

* Update cross-program-invocation.mdx

* Update calculate-rent.mdx

content/cookbook/accounts/calculate-rent.mdx

@@ -21,7 +21,7 @@ const rpc = createSolanaRpc("https://api.devnet.solana.com");
 const space = 1500n;
 
 const lamports = await rpc.getMinimumBalanceForRentExemption(space).send();
-console.log("Minimum balance for rent exception:", lamports);
+console.log("Minimum balance for rent exemption:", lamports);
 ```
 
 </Tab>

content/cookbook/programs/cross-program-invocation.mdx

@@ -7,7 +7,7 @@ A cross program invocation, is simply put calling another program's instruction
 inside our program. One best example to put forth is Uniswap's `swap`
 functionality. The `UniswapV2Router` contract, calls the necessary logic to
 swap, and calls the `ERC20` contract's transfer function to swap from one person
-to another. The same way, we can call a program's instruction to have multitude
+to another. The same way, we can call a program's instruction to have a multitude
 of purposes.
 
 Lets have a look at our first example which is the