chore(pricefeed-evm-sdk): Improve doc comments (#1521)

target_chains/ethereum/sdk/solidity/MockPyth.sol

@@ -34,6 +34,18 @@ contract MockPyth is AbstractPyth {
     // Takes an array of encoded price feeds and stores them.
     // You can create this data either by calling createPriceFeedUpdateData or
     // by using web3.js or ethers abi utilities.
+    // @note: The updateData expected here is different from the one used in the main contract.
+    // In particular, the expected format is:
+    // [
+    //     abi.encode(
+    //         PythStructs.PriceFeed(
+    //             bytes32 id,
+    //             PythStructs.Price price,
+    //             PythStructs.Price emaPrice
+    //         ),
+    //         uint64 prevPublishTime
+    //     )
+    // ]
     function updatePriceFeeds(
         bytes[] calldata updateData
     ) public payable override {