Chronos : How to generate confidence interval for prediction

[rnwang04]

Description

Provide a How-to guide for new function: predict_interval in Forecaster

1. Why the change?

Provide a How-to guide for new function: predict_interval in Forecaster

2. User API changes

No change.

3. Summary of the change

Provide a How-to guide for new function: predict_interval in Forecaster

4. How to test?

• [x] Colab test
• [x] Application test
• [x] Document test https://ruonantetdoc.readthedocs.io/en/generate_confidence_interval/doc/Chronos/Howto/index.html https://ruonantetdoc.readthedocs.io/en/generate_confidence_interval/doc/Chronos/Howto/how_to_generate_confidence_interval_for_prediction.html