Update CONTRIBUTING.md

[chtruong814]

What does this PR do ?

Update CONTRIBUTING.md

@nithinraok requested we update the Contributing guide.

• Realistically, I don't think developers currently can just run pytest and run the entire test suite successfully. I updated the guide to indicate that it is best to run the unit test suite based on what changed and reference the L0_Unit_Test scripts for specific env vars needed.
• Clarified how to trigger the Github CI with labels
• Clarified that the style command should also be selectively ran against certain files changed. Currently, not all files have styles fixed
• Updated the reviewers that should be tagged, assuming the repo is Speech focused. Need to double check those names. If non-Speech changes are made for now, I think the Nvidia NeMo developers know who to appropriate tag.

Collection: [Note which collection this PR will affect]

Changelog

• Add specific line by line info of high level changes in this PR.

Usage

• You can potentially add a usage example below

# Add a code snippet demonstrating how to use this 

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The Jenkins CI system has been replaced by GitHub Actions self-hosted runners.

The GitHub Actions CI will run automatically when the "Run CICD" label is added to the PR.
To re-run CI remove and add the label again.
To run CI on an untrusted fork, a NeMo user with write access must first click "Approve and run".

Before your PR is "Ready for review"

Pre checks:

• Make sure you read and followed Contributor guidelines
• Did you write any new necessary tests?
• Did you add or update any necessary documentation?
• Does the PR affect components that are optional to install? (Ex: Numba, Pynini, Apex etc)
  • Reviewer: Does the PR have correct import guards for all optional libraries?

PR Type:

• New Feature
• Bugfix
• Documentation

If you haven't finished some of the above items you can still open "Draft" PR.

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Contributor guidelines contains specific people who can review PRs to various areas.

Additional Information

• Related to # (issue)

[chtruong814]

@nithinraok who should be tagged here assuming the repo is just Speech?

[nithinraok]

Yes, this is good enough. May be we can be specific, something like:

Please tag @nithinraok for NeMo core and ASR related works, @blisc for TTS related.

[chtruong814]

I updated. Please take another look.

[nithinraok]

currently all issues are getting assigned to Oleksii by default. Can we also update them.

[chtruong814]

@nithinraok I created an issue to test if it was tagging someone by default, and it didn't seem to happen? Do you know of recent cases?
#15270

[nithinraok]

LGTM

[nithinraok]

@nithinraok I created an issue to test if it was tagging someone by default, and it didn't seem to happen? Do you know of recent cases? #15270

Thanks @chtruong814. We should be good then.