Add `collect-diag` makefile target, documentation

Change-Id: I581db8b52bc2b9a4b7e4c850f9b432664fbc6c92
diff --git a/Makefile b/Makefile
index bb1c0c3..24a3d76 100644
--- a/Makefile
+++ b/Makefile
@@ -77,7 +77,6 @@
 # Config file generation
 config: $(CONFIG_FILES)
 
-
 $(CONFIG_FILES):
 	ansible-playbook -i 'localhost,' --extra-vars="cord_podconfig='$(PODCONFIG_PATH)' genconfig_dir='$(GENCONFIG_D)' scenarios_dir='$(SCENARIOS_D)'" $(BUILD)/ansible/genconfig.yml $(LOGCMD)
 
@@ -100,6 +99,9 @@
 xos-update-images: clean-images
 	rm -f $(M)/start-xos $(M)/local-start-xos
 
+collect-diag:
+	$(ANSIBLE_PB) $(PI)/collect-diag-playbook.yml $(LOGCMD)
+
 compute-node-refresh:
 	$(SSH_HEAD) "cd /opt/cord/build; $(ANSIBLE_PB_MAAS) $(PI)/compute-node-refresh-playbook.yml" $(LOGCMD)
 
@@ -225,7 +227,7 @@
 	touch $@
 
 # Testing targets
-pod-test: $(M)/onboard-openstack
+pod-test: $(M)/onboard-openstack collect-diag
 	$(ANSIBLE_PB) $(PI)/pod-test-playbook.yml $(LOGCMD)
 
 # Local Targets, bring up XOS containers without a VM