add a doc with reports/insights

hawk/docs/insight_reports.md

@@ -0,0 +1,8 @@
+# Extract items where piece count could not be determined
+```sql
+select *
+from ebay_hawk_dev_db.merchandise_db.ebay_highlight eh
+ inner join merchandise_db.ebay_finding ef
+ on ef.id = eh.ebay_finding_id
+where ef.number_of_pieces is NULL
+```