Add the GitHub link to Bot's Discord description

[Mclilzee]

I wanted to take a look at the bot, so I had to google for it, and still wasn't sure if this is the right bot or not for the server. I'm still not sure, but I saw one of the maintainers have a familiar profile pic from that of Discord.

Adding the GitHub link would make it easier to find the repo for the bot, for those interested to look at it, or interested in contributing.

EDTI: After opening this Issue, I came to realize that there exists the /source command. I still think it's more subtle than having a link in the description. I can't think of any drawbacks from that. But that is only my opinion, of course.