doc: update information on output options for CommandLine interfaces

Author: satra

nipype/interfaces/base.py

@@ -1111,8 +1111,11 @@ class CommandLineInputSpec(BaseInterfaceInputSpec):
     environ = traits.DictStrStr(desc='Environment variables', usedefault=True,
                                 nohash=True)
     terminal_output = traits.Enum('stream', 'allatonce', 'file', 'none',
-                                  desc='Control terminal output', nohash=True,
-                                  mandatory=True)
+                                  desc=('Control terminal output: `stream` - displays'
+                                  'to terminal immediately, `allatonce` - waits till '
+                                  'command is finished to display output, `file` - writes'
+                                  'output to file, `none` - output is ignored'), 
+                                  nohash=True, mandatory=True)
 
 class CommandLine(BaseInterface):
     """Implements functionality to interact with command line programs