Create CODE_DESIGN.md

[steffilazerte]

Fixes #217
Add RELEASE.R and CODE-DESIGN.md as starting points (CODE-DESIGN.md in particular could be filled in more, especially "Be Careful" and a "Future ideas" section (or Roadmap) could also be added.

Also added CONTRIBUTING.md

[annecori]

This looks good to me. Wondering if @sangeetabhatia03 and or @thibautjombart want to have a look to?

[steffilazerte]

Great! I'll leave this PR open for now to see if there are any other comments. Especially if anyone remembers being confused when the first started working on EpiEstim until they understood something (then add that something to the CODE-DESIGN.md 😁)

[annecori]

@sangeetabhatia03 @thibautjombart @rebeccanash @abriz97 I would be grateful if you could have a look at this PR and add anything you can think of. Thanks!

[sangeetabhatia03]

Looks good @steffilazerte My only suggestion is to not use the double colon syntax of the package is already listed as imports, but that's a personal preference as I find that it makes the code less readable. So I'd defer to you! Otherwise I can't think of anything else off the top of my head.

[steffilazerte]

@sangeetabhatia03, pkg::fun() does make the code a bit busier for sure! However, in a package development context it does have the benefit of making it very clear what package the function comes from. If we don't use that syntax, we have to either import the whole package or the functions required (listing the packages in Imports in the DESCRIPTION isn't sufficient). This can get a bit messy. Generally, best practice is to use :: as much as possible, and then use @importFrom pkg fun1 fun2 for functions that you use a lot (and which might be relatively well known functions from well known packages).

Where that line is depends on the developer 😁

[sangeetabhatia03]

Another suggestion: I think it would be good to enforce consistency using tidyverse style guide in places; specifically I am thinking using return() for early returns, and otherwise having the function return the last evaluated expression.

[steffilazerte]

Added! Just need someone to approve the PR