docs(send-slack-notification): remove outdated docs, url update (#982)

* docs(send-slack-notification): remove outdated docs, url update

* run prettier

Author: ricky-undeadcoders

actions/send-slack-message/README.md

@@ -3,7 +3,7 @@
 This is a composite GitHub Action used to send Slack messages to the Grafana workspace.
 You do not need to set up Slack webhooks in order to use this action.
 
-See the docs for the [slackapi/slack-github-action workflow](https://github.com/slackapi/slack-github-action/blob/main/README.md#technique-2-slack-app) for more info. Our installation is via Slack App.
+See the docs for the [slackapi/slack-github-action workflow](https://tools.slack.dev/slack-github-action/sending-techniques/sending-data-slack-api-method/#usage) for more info.
 
 <!-- x-release-please-start-version -->
 
@@ -98,7 +98,7 @@ jobs:
 
 | Name                | Type   | Description                                                                                                                                        |
 | ------------------- | ------ | -------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `payload`           | String | JSON payload to send. Use `payload` or `slack-message`, but not both.                                                                              |
+| `payload`           | String | JSON payload to send.                                                                                                                              |
 | `method`            | String | The Slack API method to call.                                                                                                                      |
 | `payload-templated` | String | To replace templated variables provided from the step env or default GitHub event context and payload, set the payload-templated variable to true. |
 

actions/send-slack-message/action.yaml

@@ -3,7 +3,7 @@ description: Composite action to send a Slack message
 
 inputs:
   payload:
-    description: "JSON payload to send. Use `payload` or `slack-message`, but not both"
+    description: "JSON payload to send"
     required: false
   method:
     description: "The Slack API method to call"