On-demand reporting docs

Author: Spikatrix

docs/guides/images/api_keys.png

@@ -16,11 +16,52 @@ This feature is in beta
 
 :::
 
-CodeRabbit offers a way to generate on-demand reports using the [API](https://api.coderabbit.ai/api/swagger/).
-You will be able to use the API by creating an [API key](https://app.coderabbit.ai/settings/api-keys).
+CodeRabbit offers a way to generate on-demand reports using the [CodeRabbit API](https://api.coderabbit.ai/api/swagger/).  
+You will need an API Key to access the CodeRabbit API and generate an on-demand report.
 
+## Create an API key
 
-On-demand report input schema:
+Sign into your CodeRabbit account and navigate to the the [**API Keys**](https://app.coderabbit.ai/settings/api-keys) page under 'Organization Settings' in the left sidebar.  
+Click on the **Create API Key** button and enter a name for the API Key.  
+Copy the API key and keep it safe as it won't be visible again.
+
+![API Keys](./images/api_keys.png)
+
+## Generate an On-demand report
+
+Once you have the API key, pass it in the `x-coderabbitai-api-key` header when calling the API:
+
+```sh
+curl -X 'POST' \
+  'https://api.coderabbit.ai/api/v1/report.generate' \
+  -H 'accept: application/json' \
+  -H 'x-coderabbitai-api-key: cr-xxxxxxxxxxxxx' \
+  -H 'Content-Type: application/json' \
+  -d '{
+    "from": "2024-05-01",
+    "to": "2024-05-15"
+  }'
+```
+
+Sample output:
+
+```sh
+[
+  {
+    "group": "Developer Activity",
+    "report": "*Developer Activity*:\n\n 🟢 **Update README.md** [#10](https://gitlab.com/master-group123/sub-group/project1/-/merge_requests/10)\n• Summary: The change updates the project description and modifies a section header for clearer instructions.\n• Last activity: 1 day ago, mergeable\n• Insights:\n - :magnifying_glass: @user2 Suggested updating the wording to make it clearer"
+  }
+]
+```
+
+
+:::info
+
+If you get a 401 UNAUTHORIZED error, check if you're passing the right API key in the `x-coderabbitai-api-key` header
+
+:::
+
+The on-demand report generation endpoints take in inputs as per the schema shown below:
 
 ```mdx-code-block
 <ReportSchema />