Add topics for 'Say'

[miickel]

closes #823

[ilya-khadykin]

Thanks for the PR!

I've left a comment, please take a look

[ilya-khadykin]

We've switched to snake_case naming convention for topics to increase consistency among tracks, so could you please choose them from the following list - https://github.com/exercism/problem-specifications/blob/master/TOPICS.txt

[ilya-khadykin]

Thanks, @miickel

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 😃

Just for future reference a guide of how to write good commit messages - https://chris.beams.io/posts/git-commit/#seven-rules