Make `gurkult/gurkbot` the default repo.

[vivekashok1221]

Currently, if a repository is not mentioned when the !github command is invoked, the repository will default to the following:

• gurkult/gurkbot if the command is invoked in #dev-gurkbot
• gurkult/py-gurklang if the command is invoked in #dev-gurklang
• gurkult/reagurk if invoked in #dev-reagurk
• gurkult/branding if invoked in #dev-branding

This is fine and good. However, the command says that the issue could not be located if it is invoked in a channel like #discussion or #bot-commands and requires the user to specify the repository.

example: When invoked in #bot-commands:

When invoked in #dev-gurkbot:

I feel we should make gurkult/gurkbot the default repository for other channels too.

[vivekashok1221]

I can work on this issue since it is very trivial.

[vivekashok1221]

Good work, @codephile1221.