docs: update webhook documentation. (#730)

Co-authored-by: Suyash Sargar <[email protected]>

docs/Configuration/webhook.md

@@ -44,6 +44,8 @@ There are many tools for this:
 - For testing and quick setup, [ngrok](https://ngrok.com/) is a useful utility that provides a publicly accessible web URL to any locally hosted application. You can put DevLake's webhook on the internet within 5 mins by following ngrok's [Getting Started](https://ngrok.com/docs/getting-started) guide. Note that, when posting to webhook, you may need to replace the `localhost` part in the webhook URL with the forwarding URL that ngrok provides.
 - If you prefer DIY, please check out open-source reverse proxies like [fatedier/frp](https://github.com/fatedier/frp) or go for the classic [nginx](https://www.nginx.com/).
 
+Note: If you post incidents using webhook due to your tool not being supported but your deployments are collected via plugins automatically, you need to re-collect data for deployments for the posted incidents to get mapped to deployments based on timestamps. This is required for Change Failure Rate (DORA) metric to show up correctly for the project.
+
 ## Troubleshooting
 
 If you run into any problems, please check the [Troubleshooting](/Troubleshooting/Configuration.md) or [create an issue](https://github.com/apache/incubator-devlake/issues).

docs/Plugins/webhook.md

@@ -14,6 +14,8 @@ In v0.14+, users can push "incidents" and "deployments" required by DORA metrics
 
 Webhooks are meant to be used at the lowest level that you want to relate incidents with deployments. For example, if you want to relate incidents at the individual service level, you will need a webhook per service. If you wish to relate incidents at the product level, you will need a webhook for the product. This is because incidents on a project will be related to the last deployment on the project with a timestamp that is before the incident's timestamp. This is true regardless of the source of incidents or deployments.
 
+Note: If you post incidents using webhook due to your tool not being supported but your deployments are collected via plugins automatically, you need to re-collect data for deployments for the posted incidents to get mapped to deployments based on timestamps. This is required for Change Failure Rate (DORA) metric to show up correctly for the project.
+
 Diagram of the relationship between incidents and deployments:
 
 ![Change Failure Reporting](/img/Metrics/cfr-definition.png)