Fix documentation about when setup.py clean is run

Author: pradyunsg

docs/html/reference/build-system/setup-py.md

@@ -56,6 +56,11 @@ by pip to avoid repeated identical builds.
 
 If this wheel generation fails, pip will attempt a direct installation instead.
 
+#### Cleanup
+
+After this, pip runs `setup.py clean` to clean up any build artifacts that
+may have been generated.
+
 ### Direct Installation
 
 When all else fails, pip will invoke `setup.py install` to install a package
@@ -70,11 +75,6 @@ For installing packages in "editable" mode
 `setup.py develop`, which will use setuptools' mechanisms to perform an
 editable/development installation.
 
-### Cleanup
-
-After attempting installation, pip may run `setup.py clean` to clean up build
-artifacts from that setuptools has generated.
-
 ## Setuptools Injection
 
 To support projects that directly use `distutils`, pip injects `setuptools` into