Update documentation for contributing a PR and add deprecation notice…

…s for PyOp and ORT server. (microsoft#6172)

CONTRIBUTING.md

@@ -1,7 +1,12 @@
 # Contributing
 
-We're always looking for your help to fix bugs and improve the product. Create a pull request and we'll be happy to take a look.
-Start by reading the [Engineering Design](./docs/InferenceHighLevelDesign.md). You can find the doxygen generated documentation [here](https://microsoft.github.io/onnxruntime/).
+We're always looking for your help to improve the product (bug fixes, new features, documentation, etc).
+
+## Contributing a code change
+* Start by reading the [Engineering Design](./docs/InferenceHighLevelDesign.md). More documentation can be found in the [docs folder](./docs/) and [here](https://microsoft.github.io/onnxruntime/).
+* If your change is non-trivial or introduces new public facing APIs (discussed in more detail below) please use the [feature request issue template](https://github.com/microsoft/onnxruntime/issues/new?template=feature_request.md) to discuss it with the team and get consensus on the basic design and direction first. For all other changes, you can directly create a pull request (PR) and we'll be happy to take a look.
+* Make sure your PR adheres to the [PR Guidelines](./docs/PR_Guidelines.md) and [Coding Conventions and Standards](./docs/Coding_Conventions_and_Standards.md) established by the team.
+* If you're unsure about any of the above and want to contribute, you're welcome to [start a discussion](https://github.com/microsoft/onnxruntime/discussions) with the team.
 
 ## Proposing new public APIs
 
@@ -47,13 +52,6 @@ For making changes to the Windows Machine Learning WinRT API, please label your
 * Note: After creating a pull request, you might not see a build getting triggered right away. One of the
 onnxruntime team members will trigger the build for you.
 
-## Coding guidelines
-
-Please see [Coding Conventions and Standards](./docs/Coding_Conventions_and_Standards.md)
-
-## Guidelines for creating a good PR (pull request)
-[PR Guidelines](./docs/PR_Guidelines.md)
-
 ## Licensing guidelines
 
 This project welcomes contributions and suggestions. Most contributions require you to

docs/PyOp.md

@@ -1,4 +1,7 @@
 # Python Operator 
+
+**Deprecation Note: This feature is deprecated and no longer supported.**
+
 The Python Operator provides the capability to easily invoke any custom Python code within a single node of an ONNX graph using ONNX Runtime. This can be useful for quicker experimentation when a model requires operators that are not officially supported in ONNX and ONNX Runtime, particularly if there is already a Python implementation for the required functionality. This should be used with discretion in production scenarios, and all security or other risks should be considered beforehand.
 
 ## Design Overview

docs/Server.md

@@ -1,4 +1,7 @@
 ## Build ONNX Runtime Server on Linux
+
+**Deprecation Note: This feature is deprecated and no longer supported.**
+
 Read more about ONNX Runtime Server [here](./ONNX_Runtime_Server_Usage.md).
 
 ### Prerequisites