Modify krel Error message when github token env not set

[DiptoChakrabarty]

What would you like to be added:

On running the krel tool when no github token env var is set the error message returned is this
validating command line options: Cannot generate release notes if GitHub token is not set

comparing to the release-notes tool the error message for the same case is this, which gives a better idea of the error
neither environment variable GITHUB_TOKENnorreplay option is set

It would be good if the krel error returned would be something similar to the release notes where we specify that the Github token is the required environment variable
validating command line options: Cannot generate release notes if GitHub token environment variable is not set

Why is this needed:

Error message sounds better compared to previous error message as it can help debug faster and identify the issue

/good-first-issue

[k8s-ci-robot]

@DiptoChakrabarty:
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In response to this:

What would you like to be added:

On running the krel tool when no github token env var is set the error message returned is this
validating command line options: Cannot generate release notes if GitHub token is not set

comparing to the release-notes tool the error message for the same case is this, which gives a better idea of the error
neither environment variable GITHUB_TOKENnorreplay option is set

It would be good if the krel error returned would be something similar to the release notes where we specify that the Github token ithe required environment variable
validating command line options: Cannot generate release notes if GitHub token environment variable is not set

Why is this needed:

Error message sounds better compared to previous error message as it can help debug faster and identify the issue

/good-first-issue

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[saschagrunert]

@DiptoChakrabarty this makes sense, are you going to work on that and propose a PR? :)

[DiptoChakrabarty]

@saschagrunert Ill keep it open for new contributors , if someone doesnt pick it up in a prolonged period Ill take it up :)

[Nawaz027]

/assign

[csantanapr]

thank you @DiptoChakrabarty 👍

[RajGM]

Hi @Nawaz027
Are you still working on this issue?

[RajGM]

Hi @DiptoChakrabarty
Can somebody else pick this up?

[DiptoChakrabarty]

Sure @RajGM if @Nawaz027 is not working on it assign yourself

[knowshan]

/assign