Add info about validation errors

Author: beschoenen

source/v1/index.html.md

@@ -132,10 +132,30 @@ To Log in and try it out hit the "Try out" button.
 }
 ```
 
+> For Error Responses With Validation Errors
+
+```json
+{
+  "success": false,
+  "error": {
+    "type": "HttpNotFoundException",
+    "message": "Page Not Found",
+    "validation_errors": {
+      "attribute": "validation error for the attribute"
+    }
+  }
+}
+```
+
 All JSON responses from the API is wrapped in a base object.
 
 Be sure to include an `Accept: application/json` header, otherwise errors like `401`, `403` & `404` will either return HTML or redirect you to the login page.
 
+<aside class="warning">
+The current version (1.4.2) returns `validation_errors` as an array of string, this behavior will change the one described on the right in the next version 1.4.3. (no release ETA)
+</aside>
+
+
 ## Headers
 
 ### Exposed Headers