Apply suggestions from code review

Co-authored-by: Sam Wilson <57262657+SamWilsn@users.noreply.github.com>

Author: gurukamath

src/ethereum/__init__.py

@@ -1,5 +1,7 @@
 """
-Introduction to Ethereum.
+Ethereum base package.
+
+### Introduction
 
 Seeing as internet connections have been vastly expanding across the
 world, spreading information has become as cheap as ever. Bitcoin, for

src/ethereum/crypto/blake2.py

@@ -154,6 +154,10 @@ def G(
     ) -> List:
         """
         The mixing function used in Blake2.
+        
+        See [RFC 7693] for more details.
+        
+        [RFC 7693]: https://datatracker.ietf.org/doc/html/rfc7693#section-3.1
 
         Parameters
         ----------