Go-github: Update teams_discussion_comments.go

[gmlewis]

Relates to: #1422 and #1387.

It seems that the original blog post that we were basing #1387 on didn't mention these changes.

This issue will be for updating teams_discussion_comments.go.

The work involved here is to update every endpoint listed here:
https://developer.github.com/v3/teams/discussion_comments/
Note that #1400 can be used as a model because most endpoints have two ways to call them: *ByID and *BySlug. The same pattern should be followed for these updates.

This would be a great PR for any new contributor to this repo or a new Go developer.
All contributions are greatly appreciated!

Feel free to volunteer for any issue and the issue can be assigned to you so that others don't attempt to duplicate the work.

Please check out our CONTRIBUTING.md guide to get started.

Thank you!

[ayzu]

Hi!

I would like to work on the issue.

[gmlewis]

Thank you, @ayzu! It is yours.

[ayzu]

Thank you, @ayzu! It is yours.

Great, thank you for the quick reply! I have created a PR.