onnxruntime

12093f46 - [docs] Update docs for adding an execution provider to refer to plugin EP docs (#27340)

[docs] Update docs for adding an execution provider to refer to plugin EP docs (#27340) ### Description <!-- Describe your changes. --> - Document plugin EPs as the recommended way to add a new EP - Deprecate old way of adding EP to ORT source - Minor clean up Preview: https://edgchen1.github.io/onnxruntime/docs/execution-providers/add-execution-provider.html ### Motivation and Context <!-- - Why is this change required? What problem does it solve? - If it fixes an open issue, please link to the issue here. --> Update documentation for adding a new EP.