hello_word added parameter to exercise placeholder

[Sukhj1nder]

Added Parameters to the Hello World file in the functions hello.

This resolves the issue #584.
TODO: Hello World - Ticked on #509

Fixes #563

[ilya-khadykin]

Judging by https://github.com/exercism/python/blob/master/exercises/hello-world/hello_world_test.py hello-world doesn't expect any parameters.
And input option is too general; name is much better

I suggest add a default parameter def hello(name='') to not confuse users

[Sukhj1nder]

@m-a-ge hope this is better 👍

[ilya-khadykin]

Thanks, @Sukhj1nder

It's a best practice to squash your commits https://github.com/exercism/docs/blob/master/contributing/git-basics.md#squashing. It isn't a big deal since I can do it myself, but it would be awesome to just click on 'Merge pull request' button 😃

Please note that there are some special 'closing issue' keywords that you can put in description of your PR and Github will take care of closing the corresponding issue automatically after merge.
It makes our work much easier. I hope this hint will help you to make your future PRs a bit better

Guide on how to write good commit messages - https://chris.beams.io/posts/git-commit/#seven-rules