api: Document DELETE ../users/{user_id} endpoint.

This adds deactivate_user to python_examples.py in zerver/openapi.
This also adds delete-user.md to templates/zerver/api and adds
delete-user to rest-endpoints.md (templates/zerver/help/include).

templates/zerver/api/deactivate-user.md

@@ -0,0 +1,39 @@
+# Deactivate a user
+
+{!api-admin-only.md!}
+
+[Deactivates a
+user](https://zulipchat.com/help/deactivate-or-reactivate-a-user)
+given their user ID.
+
+`DELETE {{ api_url }}/v1/users/{user_id}`
+
+## Usage examples
+
+{start_tabs}
+{tab|python}
+
+{generate_code_example(python)|/users/{user_id}:delete|example}
+
+{tab|curl}
+
+{generate_code_example(curl)|/users/{user_id}:delete|example}
+
+{end_tabs}
+
+## Arguments
+
+{generate_api_arguments_table|zulip.yaml|/users/{user_id}:delete}
+
+## Response
+
+#### Example response
+
+A typical successful JSON response may look like:
+
+{generate_code_example|/users/{user_id}:delete|fixture(200)}
+
+An example JSON error response when attempting to deactivate the only
+organization administrator:
+
+{generate_code_example|/users/{user_id}:delete|fixture(400)}

templates/zerver/help/include/rest-endpoints.md

@@ -30,6 +30,7 @@
 
 * [Get all users](/api/get-all-users)
 * [Get a user](/api/get-user)
+* [Deactivate a user](/api/deactivate-user)
 * [Get profile](/api/get-profile)
 * [Create a user](/api/create-user)
 * [Set "typing" status](/api/typing)

zerver/openapi/python_examples.py

@@ -242,6 +242,21 @@ def get_single_user(client):
 
     validate_against_openapi_schema(result, '/users/{user_id}', 'get', '200')
 
+@openapi_test_function("/users/{user_id}:delete")
+def deactivate_user(client):
+    # type: (Client) -> None
+
+    # {code_example|start}
+    # Deactivate a user
+    user_id = 8
+    url = 'users/' + str(user_id)
+    result = client.call_endpoint(
+        url=url,
+        method='DELETE',
+    )
+    # {code_example|end}
+    validate_against_openapi_schema(result, '/users/{user_id}', 'delete', '200')
+
 @openapi_test_function("/realm/filters:get")
 def get_realm_filters(client):
     # type: (Client) -> None
@@ -1150,6 +1165,7 @@ def test_users(client):
     create_user(client)
     get_members(client)
     get_single_user(client)
+    deactivate_user(client)
     get_profile(client)
     update_notification_settings(client)
     upload_file(client)