Update /api-documentation (#20742)

Updating for more explicit bifurcation between Open-Source API (aka config API) and the Cloud API.

docs/api-documentation.md

@@ -1,18 +1,24 @@
 # API documentation
 
+## Open-Source API
+
 :::caution
 
 For Airbyte Open-Source you don't need the API Token for Authentication!
 All endpoints are possible to access using the API without it.
 
 :::
 
-Our Configuration API is still in alpha and might change. You won’t lose any functionality, but you may need to update your code to catch up to any backwards incompatible changes in the API.
+Our Open-Source API (configuration API) is still in an alpha state and might change. You won’t lose any functionality, but you may need to update your code to catch up to any backwards incompatible changes in the API.
 
-**Check it out** [**here**](https://airbyte-public-api-docs.s3.us-east-2.amazonaws.com/rapidoc-api-docs.html)**.**
+**Check out the** [**Open-Source API documentation**](https://airbyte-public-api-docs.s3.us-east-2.amazonaws.com/rapidoc-api-docs.html)**.**
 
 Don't hesitate to ask us on [Slack](https://slack.airbyte.io), if you have any questions about it.
 
+---
+
+## Airbyte Cloud API
+
 :::info
 
 Airbyte Cloud will also support API access in 2023. See [Airbyte roadmap](https://app.harvestr.io/roadmap/view/pQU6gdCyc/airbyte-roadmap) for more details.