Update pipeline schema

stpt_pipeline/schema.py

 import voluptuous as vo
 
-schema = vo.Schema({vo.Required('datalen'): vo.Range(1, 1000)})
+schema = vo.Schema(
+    {
+        vo.Required('root_dir'): str,
+        vo.Required('output_dir'): str,
+        vo.Required('flat_file'): str,
+    }
+)