document the new ReceiptValidationError::ReceiptSizeExceeded (#2194)

* document the new `ReceiptValidationError::ReceiptSizeExceeded`

* Extend the comment about ReceiptSizeExceeded

docs/6.integrations/errors/error-implementation.md

@@ -441,6 +441,13 @@ pub enum ReceiptValidationError {
     NumberInputDataDependenciesExceeded { number_of_input_data_dependencies: u64, limit: u64 },
     /// An error occurred while validating actions of an ActionReceipt.
     ActionsValidation(ActionsValidationError),
+    /// Receipt is bigger than the limit.
+    /// ReceiptSizeExceeded means that there was a receipt above the size limit (currently 4MiB).
+    /// NEAR will refuse to execute receipts that are above the size limit.
+    /// The most likely source of such receipts would be cross-contract calls with a lot of large actions
+    /// (contract deployment, function call with large args, etc).
+    /// This error means that the user has to adjust their contract to generate smaller receipts.
+    ReceiptSizeExceeded { size: u64, limit: u64 },
 }
 ```
 
@@ -466,6 +473,9 @@ ReceiptValidationError::NumberInputDataDependenciesExceeded { number_of_input_da
 "The number of input data dependencies {} exceeded the limit {} in an ActionReceipt"
 
 ReceiptValidationError::ActionsValidation(e) 
+
+ReceiptValidationError::ReceiptSizeExceeded { size, limit }
+"The size of the receipt exceeded the limit: {} > {}",
 ```