Documentation fix for Bfg: pip, teardown

docs/core_and_modules.rst

@@ -561,6 +561,9 @@ But the main purpose of BFG is to support user-defined scenarios in python. Here
       def teardown(self):
           ''' this will be executed in each worker after the end of the test '''
           log.info("Tearing down LoadTest")
+          #It's mandatory to explicitly stop worker process in teardown
+          os._exit(0)
+          return 0
 
 2. Define your options in a config file:
 
@@ -646,7 +649,13 @@ INI file section: **[bfg]**
   Default: ``caseline``.
 
 :pip:
-  Install python modules with ``pip install --user`` before the test.
+  Install python modules with ``pip install --user`` before the test. If you need multiple modules use multiline options, i.e.:
+
+::
+
+    pip=grequests
+      msgpack
+
 
 :init_param:
   An initialization parameter that will be passed to your ``setup`` method.