Refresh development documentation

docs/development/extending-models.md

@@ -1,8 +1,8 @@
 # Extending Models
 
-Below is a list of items to consider when adding a new field to a model:
+Below is a list of tasks to consider when adding a new field to a core model.
 
-## 1. Generate and run database migration
+## 1. Generate and run database migrations
 
 Django migrations are used to express changes to the database schema. In most cases, Django can generate these automatically, however very complex changes may require manual intervention. Always remember to specify a short but descriptive name when generating a new migration.
 
@@ -14,18 +14,18 @@ Django migrations are used to express changes to the database schema. In most ca
 Where possible, try to merge related changes into a single migration. For example, if three new fields are being added to different models within an app, these can be expressed in the same migration. You can merge a new migration with an existing one by combining their `operations` lists.
 
 !!! note
-    Migrations can only be merged within a release. Once a new release has been published, its migrations cannot be altered.
+    Migrations can only be merged within a release. Once a new release has been published, its migrations cannot be altered (other than for the purpose of correcting a bug).
 
 ## 2. Add validation logic to `clean()`
 
-If the new field introduces additional validation requirements (beyond what's included with the field itself), implement them in the model's `clean()` method. Remember to call the model's original method using `super()` before or agter your custom validation as appropriate:
+If the new field introduces additional validation requirements (beyond what's included with the field itself), implement them in the model's `clean()` method. Remember to call the model's original method using `super()` before or after your custom validation as appropriate:
 
 ```
 class Foo(models.Model):
 
     def clean(self):
 
-        super(DeviceCSVForm, self).clean()
+        super().clean()
 
         # Custom validation goes here
         if self.bar is None:
@@ -38,7 +38,7 @@ Add the name of the new field to `csv_headers` and included a CSV-friendly repre
 
 ## 4. Update relevant querysets
 
-If you're adding a relational field (e.g. `ForeignKey`) and intend to include the data when retreiving a list of objects, be sure to include the field using `prefetch_related()` as appropriate. This will optimize the view and avoid excessive database lookups.
+If you're adding a relational field (e.g. `ForeignKey`) and intend to include the data when retreiving a list of objects, be sure to include the field using `prefetch_related()` as appropriate. This will optimize the view and avoid extraneous database queries.
 
 ## 5. Update API serializer
 
@@ -49,7 +49,7 @@ Extend the model's API serializer in `<app>.api.serializers` to include the new
 Extend any forms to include the new field as appropriate. Common forms include:
 
 * **Credit/edit** - Manipulating a single object
-* **Bulk edit** - Performing a change on mnay objects at once
+* **Bulk edit** - Performing a change on many objects at once
 * **CSV import** - The form used when bulk importing objects in CSV format
 * **Filter** - Displays the options available for filtering a list of objects (both UI and API)
 
@@ -59,7 +59,7 @@ If the new field should be filterable, add it to the `FilterSet` for the model.
 
 ## 8. Add column to object table
 
-If the new field will be included in the object list view, add a column to the model's table. For simple fields, adding the field name to `Meta.fields` will be sufficient. More complex fields may require explicitly declaring a new column.
+If the new field will be included in the object list view, add a column to the model's table. For simple fields, adding the field name to `Meta.fields` will be sufficient. More complex fields may require declaring a custom column.
 
 ## 9. Update the UI templates
 
@@ -76,3 +76,7 @@ Create or extend the relevant test cases to verify that the new field and any ac
 * View tests
 
 Be diligent to ensure all of the relevant test suites are adapted or extended as necessary to test any new functionality.
+
+## 11. Update the model's documentation
+
+Each model has a dedicated page in the documentation, at `models/<app>/<model>.md`. Update this file to include any relevant information about the new field.