removed troubleshooting section, add -m to testing

Author: story645

doc/devel/development_setup.rst

@@ -132,10 +132,4 @@ Optional, but recommended:
   Python packages and must be installed separately. The documentation can be
   built without Inkscape and optipng, but the build process will raise various
   warnings. If the build process warns that you are missing fonts, make sure
-  your LaTeX distribution bundles cm-super or install it separately.
-
-Troubleshooting
-===============
-*  pytest - If the test runner is failing, verify that the pytest you are using
-is installed in your environment using the ``which pytest`` and ``which python``
-commands. If the paths are not the same, install pytest in your environment. 
+  your LaTeX distribution bundles cm-super or install it separately.

doc/devel/testing.rst

@@ -258,10 +258,10 @@ Run the tests
 ^^^^^^^^^^^^^
 To run the all the tests on your installed version of Matplotlib::
 
-    pytest --pyargs matplotlib.tests
+    python -m pytest --pyargs matplotlib.tests
 
 The test discovery scope can be narrowed to single test modules or even single
 functions::
 
-    pytest --pyargs matplotlib.tests.test_simplification.py::test_clipping
+    python -m pytest --pyargs matplotlib.tests.test_simplification.py::test_clipping