started a README.md, to have a place to document modelgen commands
diff --git a/xos/tools/README.md b/xos/tools/README.md
new file mode 100644
index 0000000..ef13848
--- /dev/null
+++ b/xos/tools/README.md
@@ -0,0 +1,9 @@
+## Overview of XOS tools
+
+### modelgen
+
+Modelgen reads the XOS models and applies those models to a template to generate output. 
+
+Examples:
+  * ./modelgen -a core api.template.py > ../../xos/xosapi.py            
+  * ./modelgen -a services.hpc -b Service -b User hpc-api.template.py > ../../xos/hpcapi.py