Update README.md (#74)

RandomInsano · web-flow · commit 426572daa8ee · 2024-08-23T07:11:01.000+05:30
Quick typo
diff --git a/README.md b/README.md
@@ -46,7 +46,7 @@ a_partner = Partner(
 
 ### Sending a message to your partner
 
-* The partner is now setup we can build and AS2 message
+* The partner is now setup we can build an AS2 message
 ```python
 from pyas2lib.as2 import Message
 
