updated guidlines

CONTRIBUTING.rst

@@ -109,35 +109,9 @@ Before you submit a pull request, check that it meets these guidelines:
 Tips
 ----
 
+To run a subset of tests::
 
-- Install dev requirements
-
-.. code-block:: console
-
-    $ pip install -r requirements_dev.txt
-
-- Or just install pytest
-
-.. code-block:: console
-
-    $ pip install pytest
-
-
-- you can run tests individually for each translator by passing the prefix **test_** followed by the translator name as an argument to pytest.
-
-.. code-block:: console
-
-    $ pytest test_google_trans
-    $ pytest test_linguee
-    $ pytest test_mymemory
-    $ pytest test_pons
-
-- Alternatively, you can run the test suite
-
-.. code-block:: console
-
-    $ pytest -ra
-
+$ pytest -ra
 
 
 Deploying