Create handling-exception-notes.md

[MaxenceGui]

Pull request to add handling and raising exceptions in Python training

• Reference issue #113

• [x] Read and take note on Real Python Exception Tutorial

• [x] Write the documentation that will guide CFIA Handling and Raising Exception

• [x] Modify TRAINING.md file to add the documentation to the backend developer training

[MaxenceGui]

Suggest removing the -notes.md and splitting the french and english into two markdowns (handling-exception-training.md and handling-exception-training.fr-ca.md) as it's a bit unwieldy to have both in the same file.

Implement your request

[MaxenceGui]

@RussellJimmies if it's ok with you, we can merge these files and open an issue to review and correct their grammar since they are big files.