updated docs strings and added README.md

mail_intake/models/__init__.py

@@ -1,27 +1,26 @@
 """
+# Summary
+
 Domain models for Mail Intake.
 
----
-
-## Summary
-
 This package defines the **canonical, provider-agnostic data models**
 used throughout the Mail Intake ingestion pipeline.
 
 Models in this package:
-- Represent fully parsed and normalized mail data
-- Are safe to persist, serialize, and index
-- Contain no provider-specific payloads or API semantics
-- Serve as stable inputs for downstream processing and analysis
+
+- Represent fully parsed and normalized mail data.
+- Are safe to persist, serialize, and index.
+- Contain no provider-specific payloads or API semantics.
+- Serve as stable inputs for downstream processing and analysis.
 
 These models form the core internal data contract of the library.
 
 ---
 
-## Public API
+# Public API
 
-    MailIntakeMessage
-    MailIntakeThread
+- `MailIntakeMessage`
+- `MailIntakeThread`
 
 ---
 """