Add "What is Airbyte" section to homepage (#36329)

Co-authored-by: Natalie Kwong <38087517+nataliekwong@users.noreply.github.com>

docs/readme.md

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 # Welcome to Airbyte Docs
+## What is Airbyte?
+
+Airbyte is an open-source data movement infrastructure for building extract and load (EL) data pipelines. It is designed for versatility, scalability, and ease-of-use. 
+
+There are three major components to know in Airbyte: 
+
+1. **The connector catalog**
+   * **350+ pre-built connectors**: Airbyte’s connector catalog comes “out-of-the-box” with over 350 pre-built connectors. These connectors can be used to start replicating data from a source to a destination in just a few minutes. 
+   * **No-Code Connector Builder**: You can easily extend Airbyte’s functionality to support your custom use cases through tools like the [No-Code Connector Builder](https://docs.airbyte.com/connector-development/connector-builder-ui/overview). 
+2. **The platform:** Airbyte’s platform provides all the horizontal services required to configure and scale data movement operations, available as [cloud-managed](https://airbyte.com/product/airbyte-cloud) or [self-managed](https://airbyte.com/product/airbyte-enterprise).
+3. **The user interface:** Airbyte features a UI, [**PyAirbyte**](https://docs.airbyte.com/pyairbyte) (Python library), [**API**](https://docs.airbyte.com/api-documentation), and [**Terraform Provider**](https://docs.airbyte.com/terraform-documentation) to integrate with your preferred tooling and approach to infrastructure management. 
 
-Whether you are an Airbyte user or contributor, we have docs for you!
+Airbyte is suitable for a wide range of data integration use cases, including AI data infrastructure and EL(T) workloads. Airbyte is also [embeddable](https://airbyte.com/product/powered-by-airbyte) within your own application or platform to power your product.
 
 ## For Airbyte Cloud users