add changelog

Author: icebob

CHANGELOG.md

@@ -0,0 +1,16 @@
+--------------------------------------------------
+<a name="0.6.6"></a>
+# 0.6.6 (2018-04-04)
+
+# Access to the original object in custom validator [#5](https://github.com/icebob/fastest-validator/issues/5)
+
+```js
+const schema = {
+    email: { 
+        type: "custom", 
+        check(value, schema, stack, obj) {
+            return obj.username || obj.email ? null : this.makeError(...);
+        }
+    }
+};
+```