updated docs strings and added README.md

mail_intake/credentials/__init__.py

@@ -1,10 +1,8 @@
 """
+# Summary
+
 Credential persistence interfaces and implementations for Mail Intake.
 
----
-
-## Summary
-
 This package defines the abstractions and concrete implementations used
 to persist authentication credentials across Mail Intake components.
 
@@ -14,20 +12,21 @@ credential acquisition, validation, and refresh, while implementations
 within this package are responsible solely for storage and retrieval.
 
 The package provides:
-- A generic ``CredentialStore`` abstraction defining the persistence contract
-- Local filesystem–based storage for development and single-node use
-- Distributed, Redis-backed storage for production and scaled deployments
+
+- A generic `CredentialStore` abstraction defining the persistence contract.
+- Local filesystem–based storage for development and single-node use.
+- Distributed, Redis-backed storage for production and scaled deployments.
 
 Credential lifecycle management, interpretation, and security policy
 decisions remain the responsibility of authentication providers.
 
 ---
 
-## Public API
+# Public API
 
-    CredentialStore
-    PickleCredentialStore
-    RedisCredentialStore
+- `CredentialStore`
+- `PickleCredentialStore`
+- `RedisCredentialStore`
 
 ---
 """