Update DB - Schema

DB - Schema.-.md

@@ -13,18 +13,28 @@ This chapter contains the structure of our internal database tables.
 
 ### Group
 
-- Name
+- Name (str)
+- UID*
 
 ### UserxGroup
 
-- User
-- Group
+- User (ref)
+- Group (ref)
 
 ### GroupxRecordType
 
-- Group
-- Recordtype
+- Group (ref)
+- Recordtype (ref)
 
 ### RecordType
 
-- Name
+- Name (str)
+
+### RecordAttribute
+
+- RecordType (ref)
+- Value (str)
+- Datatype (str)
+- Locked (bool)
+- Unique (bool)
+-