Fix typo in beforeTx description

Author: FranciZ

README.md

@@ -156,7 +156,7 @@ Emits the block that is about to be processed.
 Emits the results of the processing a block.
 
 #### `beforeTx`
-Emits the Transaction that I about to be processed.
+Emits the Transaction that is about to be processed.
 
 #### `afterTx`
 Emits the result of the transaction.