start documenting the draft-4 changes

Author: mr-c

draft-4/CommandLineTool.yml

@@ -38,8 +38,12 @@ $graph:
     - |
       ## Introduction to draft 4
 
-      This specification represents the third milestone of the CWL group.
-      Since draft-3, this draft introduces the following major changes and additions:
+      This specification represents the fourth milestone of the CWL group.
+      Since draft-3, this draft introduces the following changes and additions:
+
+        * Preliminary support for initialWorkDir & the Directory type
+        * "id: name" is now just "name"; "class: Classname" is now just
+          "Classtname".
 
       ## Purpose
 

draft-4/Workflow.yml

@@ -34,10 +34,10 @@ $graph:
 
       ## Introduction to draft 4
 
-      This specification represents the fourth milestone of the CWL group.  Since
-      draft-3, this draft introduces the following changes and additions:
+      This specification represents the fourth milestone of the CWL group.
+      Since draft-3, this draft introduces the following changes and additions:
 
-        * TBD
+        * The 'inputs' and 'outputs' fields have been renamed 'in' and 'out'.
 
       ## Purpose
 
@@ -469,4 +469,4 @@ $graph:
   extends: "#ProcessRequirement"
   doc: |
     Indicate that the workflow platform must support the `valueFrom` field
-    of [WorkflowStepInput](#WorkflowStepInput).
+    of [WorkflowStepInput](#WorkflowStepInput).