revised assignment

assignments/src/MV3500Cohort2021JulySeptember/homework4/README.md

-## Homework 4: DIS Behavior Modeling
+## Revised Homework 4: DIS Specification Review and Feedback
+
+Deliverables:
+* read descriptions for each PDU family and type
+* consider which hold potential use for your thesis and your warfare community
+* consider whether any message types of interest might be missing
+
+A form is being prepared to facilitate collection of responses.
+
+
+## (prior) Homework 4: DIS Behavior Modeling
 
 Deliverables: