Add issue template for documentation bugs

[ByteHamster]

Checklist

• I have used the search function for open and closed issues to see if someone else has already submitted the same feature request.
• I will describe the problem with as much detail as possible.
• This request contains only one single feature, not a list of multiple (related) features. Please link related feature requests.

KaMPIng version

0.1.1

Problem you may be having, or feature you want

Wanted to report a problem in the documentation and was asked code, mpi version, hardware architecture, etc

Suggested solution

Add a new issue template for documentation bugs. Might even automatically apply the documentation label.

[niklas-uhl]

@lukashuebner I think you added the issue templates. Could you look into that?