Add reference to QuantumArithmetic library

[fedimser]

• This is Q# library implementing various integer arithmetic algorithms with quantum integers. It includes algorithms for addition, subtraction, comparison, multiplication, division, modular exponentiation, square root and greatest common divisor.
• The library is located here: https://github.com/fedimser/quant-arith-re
• Adding it as requested in Consider adding your library to the list of Q# libraries in qsharp repo fedimser/quant-arith-re#1

[fedimser]

I am not sure if I specified github refspec correctly, please check this. My "qsharp.json" is in the root of repository, this is why "path" is empty.

[fedimser]

Thank you for the fix and accepting the PR!
If you (and you colleagues) like the library, I would appreciate a star on GitHub!
Also, if there are other, potentially useful, quantum algorithms for integer arithmetic, I would be interested in implementing them in my library, or accepting a contribution in form of a pull request.