Added necessary comments

Testing/SystemTests/lib/systemtests/systemtesting.py

@@ -1199,6 +1199,8 @@ class MantidFrameworkConfig:
         # Make sure we only save these keys here
         config.reset()
 
+        # With the default facility changed from ISIS to nothing (EMPTY),
+        # the following setting is put in place to avoid failure of tests,
         ConfigService.Instance().setString("default.facility", "ISIS")
 
         # Up the log level so that failures can give useful information

docs/source/conf.py

@@ -101,7 +101,11 @@ pygments_style = 'sphinx'
 # settings after each test.
 mantid_init_config_keys = ('datasearch.directories', 'defaultsave.directory', 'default.facility',
                            'default.instrument')
+
+# With the default facility changed from ISIS to nothing (EMPTY),
+# the following setting is put in place to avoid failure of tests,
 ConfigService.Instance().setString("default.facility", "ISIS")
+
 mantid_config_reset = [
     "_cfg['{0}'] = '{1}'".format(k,
                                  ConfigService.Instance()[k]) for k in mantid_init_config_keys