Update the readme with the latest info (DataDog#2280)

* update the readme with the latest info

* better paragraph title

Author: masci

README.md

@@ -9,12 +9,10 @@ This repository contains the Agent Integrations (also known as checks) that Data
 officially develops and supports. To add a new integration, please see the [Integrations Extras][5]
 repository and the [accompanying documentation][6].
 
-The [Datadog Agent][7] packages are equipped
-with all the checks from this repository, so to get started using them, you can
-simply [install the Agent][8] for your operating
-system.
-
-General documentation about the project can be [found here](docs/README.md)
+The [Datadog Agent][7] packages are equipped with all the Integrations from this
+repository, so to get started using them, you can simply [install the Agent][8]
+for your operating system. The [AGENT_CHANGELOG](AGENT_CHANGELOG.md) file shows
+which Integrations have been updated in each Agent version.
 
 ## Integrations as Python wheels
 
@@ -29,35 +27,17 @@ where everything falls into place in the new approach.
 | `{integration}/test_check.py` | `{integration}/tests/*.py`                        |
 | n/a                           | `{integration}/setup.py`                          |
 
-## A note about installing
-
 Now that integrations are cleanly defined as python packages, we will soon be able
 to ship them as Python wheels that will be pip-installable in the Python environment
 embedded into the Datadog Agent. This presents a paradigm change in the way we will
 be delivering standalone integration upgrades, moving away from OS-specific packages
 to idiomatic Python package delivery.
 
-Agent releases starting from version 5.21 bundle the latest wheels for any
-integration, but at the moment you can't upgrade or downgrade between releases.
-
-Each Datadog Agent release will continue to ship a set of the most up to date stable integrations available. The `requirements-agent-release.txt` file at the root of this repo is the best place to check what Integration version is shipped with each Agent.
-
-**Note** The release process is currently in flux as we move toward the ability to ship wheels independently of Agent releases. Due to this, the Changelog may show a version and release that isn't yet available to download. Please check the below table to see which Integration versions are shipped with your Agent install.
+## Contributing
 
-| Agent Version   | List of Shipped Integration Versions   |
-| --------------- | -------------------------------------- |
-| 6.2.1           | [Link][15]                             |
-| 6.3.0           | [Link][16]                             |
-
-## Quick Start
-
-Working with integrations is easy, the main page of the [development docs](docs/dev/README.md)
+Working with integrations is easy, the main page of the [development docs][6]
 contains all the info you need to get your dev enviroment up and running in minutes
-to run, test and build a Check.
-
-**Important:** the instructions are only valid for a subset of the Checks in this
-repository. Making all the checks work with the new build and test strategy is
-a work in progress. You can find the list of the checks already updated [here][14]
+to run, test and build a Check. More advanced API documentation can be found [here][20]
 
 ## Reporting Issues
 
@@ -70,15 +50,14 @@ and [knowledge base][12]. You can also visit our
 [3]: https://ci.appveyor.com/api/projects/status/8w4s2bilp48n43gw?svg=true
 [4]: https://ci.appveyor.com/project/Datadog/integrations-core
 [5]: https://github.com/DataDog/integrations-extras
-[6]: https://docs.datadoghq.com/developers/integrations/integration_sdk/
+[6]: https://docs.datadoghq.com/developers/integrations
 [7]: https://github.com/DataDog/datadog-agent
 [8]: https://docs.datadoghq.com/agent/
 [9]: https://docs.pytest.org/en/latest/
 [10]: https://packaging.python.org/tutorials/distributing-packages/
 [11]: https://docs.datadoghq.com
 [12]: https://help.datadoghq.com/hc/en-us
 [13]: https://docs.datadoghq.com/help/
-[14]: https://github.com/DataDog/integrations-core/blob/master/tasks/constants.py#L15
 [15]: https://github.com/DataDog/integrations-core/blob/6.2.1/requirements-integration-core.txt
 [16]: https://github.com/DataDog/integrations-core/blob/ea2dfbf1e8859333af4c8db50553eb72a3b466f9/requirements-agent-release.txt
 [17]: https://codecov.io/github/DataDog/integrations-core/coverage.svg?branch=master