Update test instructions

[CI skip]

Tests/README.rst

@@ -3,17 +3,21 @@ Pillow Tests
 
 Test scripts are named ``test_xxx.py`` and use the ``unittest`` module. A base class and helper functions can be found in ``helper.py``.
 
+Depedencies
+-----------
+
+    pip install coverage nose
+
+
 Execution
 ---------
 
 Run the tests from the root of the Pillow source distribution::
 
-    python selftest.py
     nosetests Tests/test_*.py
 
 Or with coverage::
 
-    coverage run --append --include=PIL/* selftest.py
     coverage run --append --include=PIL/* -m nose Tests/test_*.py
     coverage report
     coverage html
@@ -22,3 +26,4 @@ Or with coverage::
 To run an individual test::
 
     python Tests/test_image.py
+