start source with contacts

models/staging/xero/_xero_sources.yml

@@ -0,0 +1,13 @@
+version: 2
+
+sources:
+  - name: xero
+    description: Data from our Xero accounting system (tenant is Superhog Limited).
+    schema: sync_xero_superhog_limited
+    tables:
+      - name: contacts
+        identifier: contacts
+        description: |
+          Xero contacts identify other parties we transact with: customers, suppliers, employees, etc. 
+
+          The most interesting contacts are our customers.