Add deprecation warning about setup.py

docs/source/int_source.rst

@@ -25,6 +25,14 @@ running:
 
    python setup.py help
 
+.. warning::
+
+   Calling ``setup.py install`` has been deprecated for a while, and this approach is no longer
+   actively supported in novelWriter either.
+
+   In a future version, the packaging and asset build tools part of the current ``setup.py`` file
+   will be moved to another script and the ``setup.py`` file removed entirely.
+
 
 .. _a_source_depend:
 
@@ -96,11 +104,6 @@ install, here with example version number 2.0.7, but your may be different:
 
    pip install --user dist/novelWriter-2.0.7-py3-none-any.whl
 
-.. warning::
-
-   Calling ``setup.py install`` has been deprecated for a while, and this approach is no longer
-   actively supported in novelWriter either.
-
 
 .. _a_source_i18n:
 

setup.py

@@ -2064,6 +2064,14 @@ if __name__ == "__main__":
 
     # Run the standard setup
     import setuptools  # noqa: F401
+    import warnings  # noqa: F401
+    warnings.warn(
+        "The setuptools section of setup.py is deprecated and will be removed "
+        "in a future release and the setup.py file will be renamed to avoid "
+        "conflicts with build tools. Please don't use the 'setup.py install' "
+        "command, and instead use the pip and build commands.",
+        DeprecationWarning
+    )
     setuptools.setup()
 
 # END Main