Fix and Documentation

webhook_doctype field made Mandatory in Webhook
Documentation and screenshot added

frappe/docs/user/en/guides/integration/webhooks.md

@@ -0,0 +1,18 @@
+# Webhooks
+
+Webhooks are "user-defined HTTP callbacks". You can create webhook which triggers on Doc Event of the selected DocType. When the `doc_events` occurs, the source site makes an HTTP request to the URI configured for the webhook. Users can configure them to cause events on one site to invoke behaviour on another. 
+
+#### Configure Webhook
+
+To add Webhook go to
+
+> Integrations > External Documents > Webhook
+
+Webhook
+
+<img class="screenshot" src="/docs/assets/img/webhook.png">
+
+1. Select the DocType for which hook needs to be triggered e.g. Note
+2. Select the DocEvent for which hook needs to be triggered e.g. on_trash
+3. Enter a valid request URL. On occurence of DocEvent, POST request with doc's json as data is made to the URL.
+4. Optionally you can add headers to the request to be made. Useful for sending api key if required.

frappe/integrations/doctype/webhook/webhook.json

@@ -70,7 +70,7 @@
    "read_only": 0, 
    "remember_last_selected_value": 0, 
    "report_hide": 0, 
-   "reqd": 0, 
+   "reqd": 1, 
    "search_index": 0, 
    "set_only_once": 1, 
    "unique": 0
@@ -267,7 +267,7 @@
  "issingle": 0, 
  "istable": 0, 
  "max_attachments": 0, 
- "modified": "2017-09-09 13:07:14.169116", 
+ "modified": "2017-09-09 20:05:43.406391", 
  "modified_by": "Administrator", 
  "module": "Integrations", 
  "name": "Webhook",