Warn about publishing uncommitted changes

doc/release-process.rst

@@ -58,6 +58,12 @@ Ensure that ``twine`` is installed:
 
    pip install twine
 
+Ensure that all uncommitted changes are stashed, **or they will be packaged!**
+
+.. code-block:: shell
+
+   git stash
+
 Build the wheel ``./dist/pypfilt-X.Y.Z-py3-none-any.whl``:
 
 .. code-block:: shell