Document PyAssimp build and PyPI release steps. (#6795)

Add a release optional extra for build and twine, and README notes on
version bumps and pure-Python wheel limits.

Co-authored-by: Kim Kulling <kimkulling@users.noreply.github.com>

port/PyAssimp/README.md

@@ -90,3 +90,23 @@ TEST
 $ pip install -e ".[test]"
 $ LD_LIBRARY_PATH=/path/to/libassimp pytest
 ```
+
+BUILD AND DEPLOY
+----------------
+
+PyAssimp is a pure-Python package. Wheels do not bundle `libassimp`; users still
+need a matching Assimp shared library at runtime.
+
+Bump `version` in `pyproject.toml` before a release. PyPI does not allow
+replacing an existing version; yank and ship a new version if a bad release
+goes out.
+
+```console
+$ pip install -e ".[release]"
+$ python -m build
+$ twine check dist/*
+$ twine upload dist/*
+```
+
+Upload requires PyPI maintainer access for the `pyassimp` project. Prefer
+Trusted Publishing from CI when that is set up.

port/PyAssimp/pyproject.toml

@@ -17,6 +17,7 @@ dependencies = ["numpy"]
 
 [project.optional-dependencies]
 test = ["pytest>=9"]
+release = ["build", "twine"]
 
 [tool.setuptools]
 packages = ["pyassimp"]