updated docs strings and added README.md

mail_intake/models/message.py

@@ -1,10 +1,8 @@
 """
+# Summary
+
 Message domain models for Mail Intake.
 
----
-
-## Summary
-
 This module defines the **canonical, provider-agnostic representation**
 of an individual email message as used internally by the Mail Intake
 ingestion pipeline.
@@ -26,12 +24,14 @@ class MailIntakeMessage:
     Notes:
         **Guarantees:**
 
-            - This model represents a fully parsed and normalized email message
-            - It is intentionally provider-agnostic and suitable for persistence, indexing, and downstream processing
+            - This model represents a fully parsed and normalized email message.
+            - It is intentionally provider-agnostic and suitable for
+              persistence, indexing, and downstream processing.
 
         **Constraints:**
-        
-            - No provider-specific identifiers, payloads, or API semantics should appear in this model
+
+            - No provider-specific identifiers, payloads, or API semantics
+              should appear in this model.
     """
 
     message_id: str