docs: add identity state

docs/docs/concepts/identity-data-model.md

@@ -8,8 +8,14 @@ software system. It can be a customer, employee, user, contractor, or even a
 programmatic identity such as an IoT device, application, or some other type of
 "robot."
 
+:::info
+
 In ORY Kratos' terminology we call all of them "identities", and it is always
 exposed as `identity` in the API endpoints, requests, and response payloads.
+In the documentation however, we mix these words as "account recovery" or "account activation"
+is a widely accepted and understood terminology and user flow,
+while "identity recovery" or "identity activation" is not.
+:::
 
 The following examples use YAML for improved readability. However, the API
 payload is usually in JSON format. An `identity` has the following properties:
@@ -58,6 +64,28 @@ traits:
   accepted_tos: true
 ```
 
+## Identity State
+
+Identities are
+
+- `created` - via API or self-service registration);
+- `updated` - via API or self-serfice settings, account recovery, ...;
+- `disabled` - not yet implemented, see [#598](https://github.com/ory/kratos/issues/598);
+- `deleted` - via API or with a self-service flow (not yet implemented see [#596](https://github.com/ory/kratos/issues/596)).
+
+The identity state is therefore `active` or `disabled` (not yet implemented see [#598](https://github.com/ory/kratos/issues/598):
+
+<Mermaid
+  chart={`
+stateDiagram-v2
+	[*] --> Active: create
+    Active --> Active: update
+	Active --> Disabled: disable
+	Disabled --> [*]: delete
+    Disabled --> Active: enable
+`}
+/>
+
 ## Identity Traits and JSON Schemas
 
 Traits are data associated with an identity. You have to define its schema