docs/development_guide: add a note regarding autogen mocks
Adds a note regarding naming convention used for autogenerated
mock files.
@@ -216,8 +216,9 @@ GoMock's `mockgen` tool is used to autogenerate mocks from interfaces.
As an example, to create a mock client for the `Configurator` interface defined in the [configurator](https://github.com/openservicemesh/osm/tree/main/pkg/configurator) package:
```bash
-go run github.com/golang/mock/mockgen -destination=pkg/configurator/mock_client.go -package=configurator github.com/openservicemesh/osm/pkg/configurator Configurator
+go run github.com/golang/mock/mockgen -destination=pkg/configurator/mock_client_generated.go -package=configurator github.com/openservicemesh/osm/pkg/configurator Configurator
```
+*Note: Autogenerated mock file names must be prefixed with `mock_` and suffixed with `_generated` as seen above. These files are excluded from code coverage reports.*
When a mocked interface is changed, the autogenerated mock code must be regenerated.
More details can be found in [GoMock's documentation](https://github.com/golang/mock/blob/master/README.md).
