Add instructions on generating data models

Author: glopesdev

README.md

@@ -1,3 +1,14 @@
 # harp-python
 
 A low-level interface to data collected with the [Harp](https://harp-tech.org/) binary protocol.
+
+## Data model 
+
+To regenerate Pydantic data models from device schema definitions, activate a virtual environment with `dev` dependencies, and run:
+
+```
+datamodel-codegen --input ./reflex-generator/schema/device.json --output harp/model.py --output-model-type pydantic_v2.BaseModel
+```
+
+> [!IMPORTANT]
+> Currently code generation adds an unwanted field at the very end of the data model definition `registers: Optional[Any] = None`. This declaration needs to be removed for serialization to work properly.