feat: add isFemale parameter

[WatheqAlshowaiter]

Add $isFemalte parameter for arPlural() method to return the correct male/female word if you know it.

e.g: خطأ is detected as 'female' which is wrong. if you have 1 number خطأ واحدة. With my pull request I can add isFemale = false to have result خطأ واحد.

in Addition to the code modification, I have added

1. the example.
2. the corresponding test.
3. the docs modification.

[khaled-alshamaa]

Thank you @WatheqAlshowaiter for catching that buggy use case and fixing it 👍