Add raindrops approaches

[BNAndras]

@kotp, here are the two approaches I'm thinking of highlighting. Before I fill out the approach documents, do you think these approaches will be useful for students? Are there additional approaches I should highlight?

[kotp]

I see an if..else approach listed, but I do not see an if..else approach. These are both "string builder" approaches, but none use an else statement, except for the ternary use, and that is not used to build the result.

Am I missing something?

[BNAndras]

Oops, I’m so used to calling it if…else colloquially that I didn’t notice that I wasn’t even using an else.