Issue management improvements for users

[phorcys420]

It should be made clearer to the users on how to close their issues.
A good way could be to show reactions on the pinned walkthrough message, that would act like the /close and /open commands.

[phorcys420]

We should send a message telling them they can use /close as well.

I've also seen users send "/close" instead of invoking the command, we should do something about this too.