docs: add api based brains (#1685)

Issue: https://github.com/StanGirard/quivr/issues/1686

Update Quivr doc add info about api based brains

Demo:


https://github.com/StanGirard/quivr/assets/63923024/8e92420c-7bf7-4fce-bc8b-64d6479fee40

docs/docs/User_Guide/api-based-brains.md

@@ -0,0 +1,46 @@
+---
+sidebar_position: 3
+title: API Based Brains
+---
+
+:::info
+A few brains were harmed in making API based brains 🤯
+:::
+
+Quivr allows to create an API based brain. These brains can automatically call APIs to retrieve information and use it to answer questions. While an API needs to be called but all required information is not available in the conversation, Quivr will ask user to provide them before calling the API.
+
+## Demo
+
+<video width="100%" height="auto" controls>
+  <source src="/video/api-brain-demo.mp4" type="video/mp4"/>
+</video>
+
+## Configuration
+
+### Url
+
+When creating an API based brain, you need to provide the URL of the API. This is the URL that will be called when the API is invoked.
+
+### Method
+
+The method to use when calling the API. Allowed values are `GET`, `POST`, `PUT`, `DELETE`.
+
+### Params
+
+These values are passed to the API as the request body. Values are inferred from the conversation. If all required info are not furnished, the call will ask user to provide them before calling the API.
+
+<img src="/img/api-brain-params.png" alt="API Brain Params" width="100%"/>
+
+## Search Params
+
+These values are passed to the API as search params. Values are inferred from the conversation. If all required info are not furnished, the call will ask user to provide them before calling the API.
+
+Example of search param: `https://api.example.com?param1=value1&param2=value2`
+
+<img src="/img/api-brain-search-params.png" alt="API Brain Search Params" width="100%"/>
+
+## Secrets
+
+Secrets are safely stored in a vault storage database and are not exposed to the LLM. They are passed to the API as headers.
+
+<img src="/img/api-brain-secrets.png" alt="API Brain Secrets" width="100%"/>