docs: add module docstrings and README architecture/contribution section

README.md

@@ -19,6 +19,20 @@ Install ``TASI`` from the PyPi registry.
 pip install tasi
 ```
 
+### Project Architecture
+- `tasi.pose`: single object pose/timepoint representation
+- `tasi.trajectory`: ordered trajectory sequences of poses
+- `tasi.dataset`: multi-entity dataset collections and filtering
+- `tasi.io`: conversion to/from pydantic models and ORM
+- `tasi.dlr`: dataset download manager for DLR datasets
+
+### Contribution and Branching
+1. Fork the repository and create a feature branch:
+   `git checkout -b improvements/<topic>`
+2. Add tests for new behavior under `tasi/tests`
+3. Run tests: `pytest`
+4. Open a PR and link to related issues
+
 Download the latest DLR-UT version for demonstration purpose.
 ```python
 from tasi.dlr import DLRUTDatasetManager, DLRUTVersion, 

tasi/__init__.py

@@ -1,3 +1,9 @@
+"""TASI - Traffic Situation Analysis and Interpretation.
+
+This package exposes core traffic data structures and analysis tools for
+trajectories, poses, and datasets. It initializes the default logger on import.
+"""
+
 from . import _version
 from .dataset import *
 from .pose import *

tasi/base.py

@@ -9,6 +9,11 @@
 
 
 class TimestampMixin:
+    """Mixin that adds timestamp-based indexing and selection helpers.
+
+    This mixin expects a pandas object with a timestamp index level named
+    `TIMESTAMP_COLUMN` and provides convenience methods such as `att`.
+    """
 
     TIMESTAMP_COLUMN = "timestamp"