chore: fix typo in README.md

Author: Nashtare

README.md

@@ -1,6 +1,6 @@
 # retesteth
 
-A test generaion tool for the test fillers https://github.com/ethereum/tests/tree/develop/src  
+A test generation tool for the test fillers https://github.com/ethereum/tests/tree/develop/src  
 Using state transition tool [t8n](https://ethereum-tests.readthedocs.io/en/latest/t8ntool-ref.html)  
 More t8n spec docs: https://github.com/ethereum/go-ethereum/tree/master/cmd/evm  
 Execution stats: http://retesteth.ethdevops.io/