docs: iam docstrings

Issue: #13

src/iam/models.py

@@ -2,8 +2,11 @@
 Database models for the IAM module
 
 Models:
- - List: Description
- - Models: Description
+ - Permission:
+  - id[PK], resource[U1], action[U1], service_id[FK][U1]
+  - service_rel: ORM relationship over service_id FK
+  - group_rel: ORM relationship backpops to Group.permission_rel
+  - service_name: Calc property service_rel.name
 """
 from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint
 from sqlalchemy.orm import relationship