added Poland as a country which contributed to ERP5

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@12626 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/PropertySheet/PropertySheets.stx

@@ -243,6 +243,7 @@ Categories
     region/americas/south/brazil
     region/europe
     region/europe/central
+    region/europe/central/poland
     region/europe/east
     region/europe/north
     region/europe/west