docs: issue-10 📚 Add changed marker docs

README.md

@@ -35,6 +35,10 @@ Using the `ChangeDetectionMixin` the pydantic models are extended, so:
   changed fields.  
   **Note:** When using pydantic 1.x you need to use `obj.dict()` and `obj.json()`. Both
   also accept `exclude_unchanged`.
+* `obj.model_mark_changed("marker_name")` and `obj.model_unmark_changed("marker_name")`
+  allow to add arbitrary change markers. An instance with a marker will be seen as changed
+  (`obj.model_has_changed == True`). Markers are stored in `obj.model_changed_markers`
+  as a set.
 
 ### Example
 
@@ -63,6 +67,31 @@ value to `model_set_changed()` when you want to also keep track of the actual ch
 compared to the original value. Be advised to `.copy()` the original value
 as lists/dicts will always be changed in place.
 
+### Changed markers
+
+You may also just mark the model as changed. This can be done using changed markers.
+A change marker is just a string that is added as the marker, models with such an marker
+will also be seen as changed. Changed markers also allow to mark models as changed when
+related data was changed - for example to also update a parent object in the database
+when some children were changed.
+
+```python
+import pydantic
+from pydantic_changedetect import ChangeDetectionMixin
+
+class Something(ChangeDetectionMixin, pydantic.BaseModel):
+    name: str
+
+
+something = Something(name="something")
+something.model_has_changed  # = False
+something.model_mark_changed("mood")
+something.model_has_changed  # = True
+something.model_changed_markers  # {"mood"}
+something.model_unmark_changed("mood")  # also will be reset on something.model_reset_changed()
+something.model_has_changed  # = False
+```
+
 # Contributing
 
 If you want to contribute to this project, feel free to just fork the project,