docs: user docstrings

Issue: #13

src/user/models.py

@@ -2,7 +2,12 @@
 Database models for user module
 
 Models:
- - User - id[pk], email, first_name, last_name, oidc_id
+ - User:
+  - id[PK], email, first_name, last_name, oidc_id
+  - organisation_rel: ORM relationship to Organisation via OrgUsers table
+  - group_rel: ORM relationship to Group via UserGroups table
+  - organisations: Calc property list of organisation_rel.name
+  - groups: Calc property dict of {group_rel.org_rel.name: group_rel.name}
 """
 from collections import defaultdict