Merge pull request #481 from scipp/module-docs

Add top-level module docs

src/scippneutron/__init__.py

@@ -1,7 +1,16 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
-
 # flake8: noqa
+"""Neutron scattering toolkit built using scipp for Data Reduction.
+
+ScippNeutron is a generic (as in 'usable by different facilities')
+package for data processing in neutron scattering.
+It provides coordinate transformations, file I/O, and technique-specific tools.
+
+See the online documentation for user guides and the API reference:
+https://scipp.github.io/scippneutron/
+"""
+
 import importlib.metadata
 
 try: