[svn r62352] add a note about how to specify plugins

--HG--
branch : trunk

py/doc/test-config.txt

@@ -1,7 +1,20 @@
-
 Test configuration
 ========================
 
+specifying plugins
+---------------------------
+
+you can instruct py.test to use additional plugins by:
+
+* setting the PYTEST_PLUGINS environment variable
+  to a comma-separated list of plugins
+* XXX supplying "--plugins=NAME1,NAME2,..." at the command line 
+* setting "pytest_plugins='name1', 'name2'" in 
+  ``conftest.py`` files or in python test modules. 
+
+py.test will load all plugins along with their dependencies
+(plugins may specify "pytest_plugins" as well). 
+
 test option values 
 -----------------------------