V0.2.0: Support more ops and onnx model zoo models

[maxwillzq]

We bump version.py into "0.2.0"

Changes includes:

1. Add more onnx ops and onnx model zoo model (42) support.
2. Run through Meta LLAMA model end 2 end flow.
3. Add doc how to contribute new op.

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This discussion was created from the release V0.2.0: Support more ops and onnx model zoo models.