Update README.md

Author: AlexPetul

README.md

@@ -7,13 +7,17 @@ An extended JSON field for Django and Django REST framework with validation supp
 
 ## Usage
 
-Install the package:
+### Installation
+
+To install the package, run:
 
 ```text
 pip install django_custom_jsonfield
 ```
 
-Import `CustomJSONField` and define your `schema`, for example:
+### Defining a model field
+
+Import CustomJSONField and define your schema. Here’s an example of how to use it in a model:
 
 ```python
 from django.db import models
@@ -37,8 +41,8 @@ Location(coordinates={"x": 45, "z": 45})  # ValidationError
 
 ```
 
-## DRF Serializer
-Just like you use `CustomJSONField` in your models, you can use them in serializers:
+### DRF Serializers
+You can also use `CustomJSONField` in Django REST Framework serializers:
 
 ```python
 from rest_framework import serializers
@@ -49,4 +53,18 @@ class LocationSerializer(serializers.Serializer):
 
 ```
 
-This package automatically comes with openapi extension for `drf-spectacular`.
+### OpenAPI Integration
+This package includes extension for `drf-spectacular`, allowing your API documentation 
+to correctly display the expected JSON schema.
+
+## Migrating existing data
+The `CustomJSONField` does not impose constraints on existing data. 
+Therefore, you can change a field from default `JSONField` to `CustomJSONField` even if 
+some rows violate the schema. However, it is recommended to follow these steps to 
+sure a smooth transition:
+
+1. **Create a new field**: add a new field of type `CustomJSONField` to your model.
+2. **Data migration**: Perform a data migration to copy the values from the old field to the new field, ensuring the data conforms to the schema.
+3. **Replace the old field**: Remove the old field and rename the new field to match the old field's name.
+
+Following these steps will ensure that your data complies with the new schema.